High-low parameter fused salt cascade energy storage system for thermal power peak regulation and heat storage and release method

Abstract

The invention discloses a high-low parameter fused salt cascade energy storage system for thermal power peak regulation, which comprises a boiler power generation unit, and in a heat storage working mode, the boiler power generation unit is connected with a heat storage unit through a corresponding heat exchanger for heat exchange; and in the heat release working mode, the boiler power generation unit is connected with the heat release unit through the corresponding heat exchanger for heat exchange. The invention further discloses a method of the high-low parameter fused salt cascade energy storage system for thermal power peak regulation. By means of the arrangement, the high-low parameter fused salt cascade energy storage system for thermal power peak regulation solves the problem that in the prior art, wide-temperature-range heat energy cannot be adapted.

Description

Technical Field

[0001] This invention belongs to the field of energy storage device technology, and relates to a high- and low-parameter molten salt cascade energy storage system for peak shaving of thermal power plants, as well as a heat storage and release method for the high- and low-parameter molten salt cascade energy storage system for peak shaving of thermal power plants. Background Technology

[0002] In 2023, global installed capacity of sustainable energy increased by 50% year-on-year, reaching 510 gigawatts. It is projected that by 2027, renewable energy will account for over 90% of global new power generation capacity. However, clean energy is intermittent and volatile, leading to continuous fluctuations in grid load and frequency, threatening the reliable operation of the grid. Therefore, there is an urgent need for more effective peak-shaving measures to balance electricity supply and demand and ensure grid stability and security.

[0003] Grid peak shaving mainly relies on two methods: First, building pumped storage and compressed air energy storage power stations, which, while capable of peak shifting and valley filling, are costly and have limited capacity, making it difficult to cope with the peak shaving pressure after a large amount of clean energy is connected to the grid. Second, utilizing coal-fired power plants for peak shaving, which have large installed capacity and can output a large amount of peak-shaving power, and adjusting the power generation can meet certain peak-shaving needs. However, due to limitations in equipment materials and operational safety, the power generation load of coal-fired power plants can usually only be maintained at 30%-100%, making it difficult to adapt to the surge in peak-shaving demand brought about by the expansion of the proportion of renewable energy. Expanding its load regulation range is therefore urgent.

[0004] Methods to improve the adaptability of coal-fired power plants include upgrading their own equipment systems and using energy storage devices for peak shaving. Upgrading coal-fired power plants themselves can easily lead to boiler combustion instability and may also cause safety risks such as boiler tube rupture. In energy storage-assisted peak shaving, hot water tanks and electric boilers, due to their small scale, are only suitable for low-temperature thermal storage or short-term peak shaving and are not suitable for large-scale power systems. Molten salt thermal storage, with its advantages of large storage capacity, high temperature, wide operating range, high energy density, and long lifespan, has become a key research focus for improving the flexibility of coal-fired power plants.

[0005] In the flexibility retrofitting of coal-fired power units, existing molten salt energy storage solutions typically employ a single-salt, dual-tank system. This system includes a high-temperature molten salt tank and a low-temperature molten salt tank, storing molten salt at different temperatures. However, the coupling of a single-salt, dual-tank molten salt thermal storage system with a coal-fired power unit presents significant limitations. The internal circulating working fluid temperature of a coal-fired power unit spans 35-560℃, encompassing multiple grades of thermal energy. In contrast, the operating temperature range of a single type of molten salt (such as solar salt (260-570℃) or Hitec salt (180-460℃)) is fixed, failing to achieve comprehensive coverage of thermal energy across a wide temperature range. This results in difficulty in capturing low-temperature waste heat and an inability to handle high-temperature thermal energy, lacking the system's capacity for tiered storage and utilization of different grades of thermal energy. Furthermore, in terms of peak-shaving operation, the fixed temperature range of a single salt limits the range of its thermal storage / release power adjustment, making it difficult to match the wide load fluctuations required by coal-fired power units. Therefore, a superior solution is needed to address the aforementioned problems encountered in energy storage applications. Summary of the Invention

[0006] The purpose of this invention is to provide a high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants, which solves the problem that existing technologies cannot adapt to thermal energy with a wide temperature range.

[0007] Another objective of this invention is to provide a heat storage and release method for a high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants.

[0008] The first technical solution adopted in this invention is a high- and low-parameter molten salt cascade energy storage system for peak shaving of thermal power, including a boiler power generation unit. In the heat storage mode, the boiler power generation unit and the heat storage unit are connected and exchange heat through corresponding heat exchangers; in the heat release mode, the boiler power generation unit and the heat release unit are connected and exchange heat through corresponding heat exchangers.

[0009] The first technical solution adopted in this invention is further characterized by: The boiler power generation unit includes a high-pressure cylinder module, which is connected to an intermediate-pressure cylinder module via a shaft. The intermediate-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft.

[0010] The boiler power generation unit also includes a boiler superheater, which is equipped with a main steam outlet, a main steam inlet, a reheat steam outlet, and a reheat steam inlet.

[0011] The main steam outlet of the boiler superheater is connected to the high-pressure cylinder module through a pipeline. The high-pressure cylinder module is connected to the first high-temperature heater and the second high-temperature heater through two pipelines respectively. The pipeline between the high-pressure cylinder module and the second high-temperature heater is also connected to the first branch pipeline. The other end of the first branch pipeline is connected to the reheat steam inlet of the boiler superheater. The reheat steam outlet is connected to the intermediate pressure cylinder module via a pipeline. The intermediate pressure cylinder module includes a first outlet, a second outlet, a third outlet, and a fourth outlet. The first outlet is connected to a third high-temperature heater via a pipeline. The second outlet is connected to the inlet of the deaerator via a pipeline. The third outlet is connected to a fifth low-temperature heater via a pipeline. The fourth outlet is connected to the inlet of the low-pressure cylinder module via a pipeline. The low-pressure cylinder module also includes a first low-pressure cylinder outlet, a second low-pressure cylinder outlet, and a third low-pressure cylinder outlet. The first low-pressure cylinder outlet is connected to a sixth cryogenic heater via a pipe, the second low-pressure cylinder outlet is connected to a seventh cryogenic heater via a pipe, and the third low-pressure cylinder outlet is connected to a condenser via a pipe.

[0012] The first high-temperature heater is connected to the second high-temperature heater via a pipe, the second high-temperature heater is connected to the third high-temperature heater via a pipe, and the third high-temperature heater is connected to the inlet of the deaerator via a pipe. The fifth cryogenic heater is connected to the sixth cryogenic heater via a pipeline, the sixth cryogenic heater is connected to the seventh cryogenic heater via a pipeline, and the seventh cryogenic heater is connected to the air inlet of the condenser via a pipeline. The outlet of the condenser is connected to a condensate pump via a pipeline, and the other end of the condensate pump is connected to the inlet of the deaerator via a pipeline. The pipeline between the condensate pump and the deaerator also exchanges heat through the seventh cryogenic heater, the sixth cryogenic heater and the fifth cryogenic heater in sequence. The outlet of the deaerator is connected to a feedwater pump via a pipeline. The other end of the feedwater pump is connected to the main steam inlet via a pipeline. The pipeline between the feedwater pump and the main steam inlet also exchanges heat through a third high-temperature heater, a second high-temperature heater, and a first high-temperature heater in sequence.

[0013] The thermal storage unit includes a high-temperature solar salt tank, which is connected to a first steam-molten salt heat exchanger via a pipeline. The first steam-molten salt heat exchanger is connected to a second steam-molten salt heat exchanger via a pipeline. The second steam-molten salt heat exchanger is connected to a low-temperature solar salt pump via a pipeline. The low-temperature solar salt pump is connected to the low-temperature solar salt tank via a pipeline. The thermal storage unit also includes a low-temperature Hitec salt tank, which is connected to a low-temperature Hitec salt pump via a pipeline. The low-temperature Hitec salt pump is connected to a phase change heat exchanger via a pipeline, and the phase change heat exchanger is connected to a high-temperature Hitec salt tank via a pipeline. The inlet of the first steam-molten salt heat exchanger is connected to the main steam outlet of the boiler superheater through a pipeline. The outlet of the first steam-molten salt heat exchanger is connected to the inlet of the phase change heat exchanger through a pipeline. The outlet of the phase change heat exchanger is connected to a conventional heat exchanger through a pipeline. The outlet of the conventional heat exchanger is connected to the inlet of the feedwater pump through a pipeline. The outlet of the water pump is connected to the air outlet of the first high-temperature heater through a pipeline, and the pipeline between the water pump and the first high-temperature heater exchanges heat through a conventional heat exchanger. The inlet of the second steam-molten salt heat exchanger is connected to the reheat steam outlet of the boiler superheater via a pipeline, and the outlet of the second steam-molten salt heat exchanger is connected to the inlet of the low-pressure cylinder module via a pipeline.

[0014] The heat release unit includes a high-temperature solar salt tank, which is connected to a high-temperature solar salt pump via a pipeline. The high-temperature solar salt pump is connected to a molten salt-feedwater evaporator via a pipeline, and the molten salt-feedwater evaporator is connected to a low-temperature solar salt tank via a pipeline. The inlet of the molten salt-feedwater evaporator is connected to the outlet of the first high-temperature heater via a pipeline, and the outlet of the molten salt-feedwater evaporator is connected to the reheat steam inlet via a pipeline. The heat release unit also includes a high-temperature Hitec salt tank, which is connected to a molten salt-feed water heat exchanger via a pipe, and a low-temperature Hitec salt tank via a pipe. The inlet of the molten salt-feed water heat exchanger is connected to the outlet of the feed water pump via a pipe, and the outlet of the molten salt-feed water heat exchanger is connected to the outlet of the first high-temperature heater via a pipe.

[0015] Another technical solution adopted in this invention is a method for a high- and low-parameter molten salt cascade energy storage system for peak shaving of thermal power plants, comprising the following steps: In the thermal storage working mode, the solar salt in the low-temperature solar salt tank exchanges heat through a second steam-molten salt heat exchanger and a first steam-molten salt heat exchanger, and then flows into the high-temperature solar salt tank; the Hitec salt in the low-temperature Hitec salt tank exchanges heat through a phase change heat exchanger and then flows into the high-temperature Hitec salt tank. In the heat release mode, the high-temperature solar salt in the high-temperature solar salt tank flows into the low-temperature solar salt tank after heat exchange through the molten salt-feedwater evaporator; the high-temperature Hitec salt in the high-temperature Hitec salt tank flows into the low-temperature Hitec salt tank after heat exchange through the molten salt-feedwater heat exchanger.

[0016] The beneficial effects of this invention are: This invention relates to a high- and low-parameter molten salt cascade energy storage system for thermal power peak shaving. By setting up a multi-tank molten salt system, it constructs molten salt thermal storage and heat exchange processes with different parameters, thereby realizing the cascade storage and utilization of energy. This molten salt energy storage system can generate steam with higher parameters. During the thermal storage process, two types of molten salt with different parameters are used to store part of the thermal energy of the main steam and reheat steam, effectively reducing power generation while ensuring the quality of reserved thermal energy. During the thermal storage process, the waste heat of the main steam and reheat steam is used to heat the feedwater and condensate in stages, effectively improving energy utilization. During the heat release process, while ensuring that the boiler load remains unchanged, high-temperature solar salt is used to heat the final feedwater to the state of cold reheat steam; high-temperature Hitec salt is used to heat the feedwater in the regenerative system, reducing the amount of steam extracted by the turbine, thereby effectively increasing power generation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the high and low parameter molten salt cascade energy storage system for peak shaving of thermal power plants under the thermal storage working mode of the present invention. Figure 2 This is a schematic diagram of the overall structure under the heat release working mode of the present invention; Figure 3 This is a schematic diagram of the overall structure of the boiler power generation unit of the present invention.

[0018] In the diagram: 1. High-temperature solar salt tank; 2. Low-temperature solar salt tank; 3. High-temperature Hitec salt tank; 4. Low-temperature Hitec salt tank; 5. First steam-molten salt heat exchanger; 6. Second steam-molten salt heat exchanger; 7. Phase change heat exchanger; 8. Conventional heat exchanger; 9. Low-temperature solar salt pump; 10. Low-temperature Hitec salt pump; 11. Molten salt. 12. Feedwater evaporator, 13. Molten salt-feedwater heat exchanger, 14. High-temperature solar salt pump, 15. High-temperature Hitec salt pump, 16. Boiler superheater, 17. First high-temperature heater, 18. Second high-temperature heater, 19. Third high-temperature heater, 10. Fifth low-temperature heater, 11. Sixth low-temperature heater, 12. Seventh low-temperature heater, 15. Condenser, 16. Condensate pump, 17. Deaerator, 18. Feedwater pump. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 and Figure 3 As shown, in the system's thermal storage operation mode, liquid low-temperature solar salt stored in the low-temperature solar salt tank 2 is drawn and pressurized by the low-temperature solar salt pump 9. The pressurized low-temperature solar salt first enters the second steam-molten salt heat exchanger 6, where it exchanges heat with high-parameter main steam from the boiler superheater outlet. The main steam releases heat to heat the solar salt, reducing its own temperature and pressure. The solar salt, initially heated by the second steam-molten salt heat exchanger 6, then enters the first steam-molten salt heat exchanger 5, where it further exchanges heat with medium-to-high-parameter reheat steam from the boiler reheater outlet. The reheat steam releases heat to continue heating the solar salt, cooling itself. After two stages of heating by the main steam and reheat steam, the solar salt temperature significantly increases, reaching the preset high-temperature thermal storage temperature (e.g., 500-600℃), becoming high-temperature solar salt. The high-temperature solar salt is then transported to the high-temperature solar salt tank 1 for storage.

[0021] Liquid cryogenic Hitec salt stored in cryogenic Hitec salt tank 4 is drawn and pressurized by cryogenic Hitec salt pump 10. The pressurized cryogenic Hitec salt then enters phase change heat exchanger 7. In this heat exchanger, the Hitec salt exchanges heat with the residual heat of the main steam, whose temperature has decreased after heat exchange in the first steam-molten salt heat exchanger 5, absorbing its heat. During the heat exchange process, the main steam, whose temperature has decreased, undergoes a phase change, releasing a large amount of latent heat, allowing the cryogenic Hitec salt to store a significant amount of heat. The heated Hitec salt then reaches its preset high-temperature heat storage temperature (e.g., 300-350°C), becoming high-temperature Hitec salt. The high-temperature Hitec salt is then transported to high-temperature Hitec salt tank 3 for storage.

[0022] In the energy storage process, in addition to the aforementioned molten salt energy storage, the system also optimizes the utilization of waste heat from main steam and reheat steam. In the first steam-molten salt heat exchanger 5 and the second steam-molten salt heat exchanger 6, after the steam releases heat to the molten salt, it still retains a certain temperature and pressure, which can be introduced into the conventional regenerative system of thermal power plants to heat feedwater or condensate, thereby reducing the demand for turbine extraction steam in the regenerative system, indirectly reducing the unit's power generation capacity, and improving the overall cycle efficiency. Specifically, the cooled main steam from the phase change heat exchanger 7 is used to heat part of the feedwater pump through the ordinary heat exchanger 8 before being fed to the final feedwater; the cooled reheat steam from the second steam-molten salt heat exchanger 6 is fed into the low-pressure cylinder inlet to continue doing work.

[0023] enter Figure 2 and Figure 3 As shown, the system's heat release operating mode is described in the following document. Figure 2 : The high-temperature solar salt stored in the high-temperature solar salt tank 1 is drawn out and pressurized by the high-temperature solar salt pump 13. The pressurized high-temperature solar salt then enters the molten salt system. Feedwater evaporator 11. In molten salt In the feedwater evaporator 11, high-temperature solar salt exchanges heat with high-pressure feedwater from the feedwater pump outlet, which is about to enter the boiler economizer. The high-temperature solar salt releases a large amount of heat, heating the high-pressure feedwater to a superheated steam state. The heated high-pressure feedwater is then sent into the cold reheat steam, thereby increasing the unit's power generation capacity. After releasing heat, the solar salt's temperature decreases, becoming low-temperature solar salt, which is then sent back to the low-temperature solar salt tank 2.

[0024] High-temperature Hitec salt stored in high-temperature Hitec salt tank 3 is drawn and pressurized by high-temperature Hitec salt pump 14. The pressurized high-temperature Hitec salt then enters molten salt-feedwater heat exchanger 12. In molten salt-feedwater heat exchanger 12, the high-temperature Hitec salt exchanges heat with the feedwater in the regenerative system, releasing heat to heat the feedwater to a higher temperature. Because its temperature has been preheated, the amount of heat required to enter these heaters is reduced, thereby reducing the amount of steam extracted from the turbine to heat this water (i.e., reducing turbine extraction losses). Reduced extraction means more steam can continue to expand and do work in each stage of the turbine, increasing the turbine's effective output power and thus improving the unit's total power generation. After releasing heat, the Hitec salt's temperature decreases (or it undergoes a phase change), becoming low-temperature Hitec salt, which is then returned to low-temperature Hitec salt tank 4.

[0025] Through the above process, during the heat release process of the molten salt energy storage system, the superheated section corresponds to the high-parameter molten salt, and the heated section corresponds to the low-parameter molten salt, realizing the cascade utilization of energy. This allows for the generation of steam with higher parameters to meet the power generation needs of subsequent processes.

[0026] Through the aforementioned energy storage scheme, the system can generate steam with higher parameters. When used for power generation, this can improve the system's output power and power generation efficiency; when used for heating, the higher steam parameters can adapt to a wider range of heating scenarios. This energy storage scheme eliminates the shortcomings of the dual-tank molten salt system and has broad application prospects in areas such as deep peak shaving of thermal power units, industrial heating, steam power generation, and waste heat utilization.

[0027] Example 1 like Figure 1 and Figure 2 As shown in this embodiment, the high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants includes a boiler power generation unit. In the thermal storage mode, the boiler power generation unit and the thermal storage unit are connected for heat exchange via corresponding heat exchangers; in the heat release mode, the boiler power generation unit and the heat release unit are connected for heat exchange via corresponding heat exchangers. The boiler power generation unit includes a high-pressure cylinder module, which is connected to a medium-pressure cylinder module via a shaft. The medium-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft.

[0028] Example 2 like Figure 1 and Figure 2As shown, the high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power proposed in this embodiment includes a boiler power generation unit. In the thermal storage mode, the boiler power generation unit and the thermal storage unit are connected for heat exchange through corresponding heat exchangers; in the heat release mode, the boiler power generation unit and the heat release unit are connected for heat exchange through corresponding heat exchangers. The boiler power generation unit includes a high-pressure cylinder module, which is connected to a medium-pressure cylinder module via a shaft. The medium-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft. The boiler power generation unit also includes a boiler superheater 15, which has a main steam outlet, a main steam inlet, a reheat steam outlet, and a reheat steam inlet.

[0029] Example 3 like Figure 1 , Figure 2 and Figure 3 As shown, the high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power proposed in this embodiment includes a boiler power generation unit. In the thermal storage mode, the boiler power generation unit and the thermal storage unit are connected for heat exchange through corresponding heat exchangers; in the heat release mode, the boiler power generation unit and the heat release unit are connected for heat exchange through corresponding heat exchangers. The boiler power generation unit includes a high-pressure cylinder module, which is connected to a medium-pressure cylinder module via a shaft. The medium-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft. The boiler power generation unit also includes a boiler superheater 15, which has a main steam outlet, a main steam inlet, a reheat steam outlet, and a reheat steam inlet. The main steam outlet of the boiler superheater 15 is connected to the high-pressure cylinder module via a pipeline. The high-pressure cylinder module is connected to the first high-temperature heater 1501 and the second high-temperature heater 1502 via two pipelines respectively. A first branch pipeline is also connected to the pipeline between the high-pressure cylinder module and the second high-temperature heater 1502. The other end of the first branch pipeline is connected to the reheat steam inlet of the boiler superheater 15. The reheat steam outlet is connected to the intermediate-pressure cylinder module via a pipeline. The intermediate-pressure cylinder module includes a first outlet, a second outlet, a third outlet, and a fourth outlet. The first outlet of the intermediate-pressure cylinder is connected to... The system is equipped with a third high-temperature heater 1503, a second outlet of the intermediate-pressure cylinder connected to the inlet of the deaerator 1509 via a pipe, a third outlet of the intermediate-pressure cylinder connected to a fifth low-temperature heater 1504 via a pipe, and a fourth outlet of the intermediate-pressure cylinder connected to the inlet of the low-pressure cylinder module via a pipe. The low-pressure cylinder module also includes a first outlet, a second outlet, and a third outlet of the low-pressure cylinder. The first outlet of the low-pressure cylinder is connected to a sixth low-temperature heater 1505 via a pipe, the second outlet of the low-pressure cylinder is connected to a seventh low-temperature heater 1506 via a pipe, and the third outlet of the low-pressure cylinder is connected to a condenser 1507 via a pipe.

[0030] Example 4 like Figure 1 , Figure 2and Figure 3As shown, the high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power proposed in this embodiment includes a boiler power generation unit. In the thermal storage mode, the boiler power generation unit and the thermal storage unit are connected for heat exchange through corresponding heat exchangers; in the heat release mode, the boiler power generation unit and the heat release unit are connected for heat exchange through corresponding heat exchangers. The boiler power generation unit includes a high-pressure cylinder module, which is connected to a medium-pressure cylinder module via a shaft. The medium-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft. The boiler power generation unit also includes a boiler superheater 15, which has a main steam outlet, a main steam inlet, a reheat steam outlet, and a reheat steam inlet. The main steam outlet of the boiler superheater 15 is connected to the high-pressure cylinder module via a pipeline. The high-pressure cylinder module is connected to the first high-temperature heater 1501 and the second high-temperature heater 1502 via two pipelines respectively. A first branch pipeline is also connected to the pipeline between the high-pressure cylinder module and the second high-temperature heater 1502. The other end of the first branch pipeline is connected to the reheat steam inlet of the boiler superheater 15. The reheat steam outlet is connected to the intermediate-pressure cylinder module via a pipeline. The intermediate-pressure cylinder module includes a first outlet, a second outlet, a third outlet, and a fourth outlet. The first outlet of the intermediate-pressure cylinder is connected to... The system is equipped with a third high-temperature heater 1503, a second outlet of the intermediate-pressure cylinder connected to the inlet of the deaerator 1509 via a pipe, a third outlet of the intermediate-pressure cylinder connected to a fifth low-temperature heater 1504 via a pipe, and a fourth outlet of the intermediate-pressure cylinder connected to the inlet of the low-pressure cylinder module via a pipe. The low-pressure cylinder module also includes a first outlet, a second outlet, and a third outlet of the low-pressure cylinder. The first outlet of the low-pressure cylinder is connected to a sixth low-temperature heater 1505 via a pipe, the second outlet of the low-pressure cylinder is connected to a seventh low-temperature heater 1506 via a pipe, and the third outlet of the low-pressure cylinder is connected to a condenser 1507 via a pipe.The first high-temperature heater 1501 is connected to the second high-temperature heater 1502 via a pipeline. The second high-temperature heater 1502 is connected to the third high-temperature heater 1503 via a pipeline. The third high-temperature heater 1503 is connected to the inlet of the deaerator 1509 via a pipeline. The fifth low-temperature heater 1504 is connected to the sixth low-temperature heater 1505 via a pipeline. The sixth low-temperature heater 1505 is connected to the seventh low-temperature heater 1506 via a pipeline. The seventh low-temperature heater 1506 is connected to the air inlet of the condenser 1507 via a pipeline. The outlet of the condenser 1507 is connected to the condensate pump 1508 via a pipeline. The other end of the condensate pump 1508 is connected to the inlet of the deaerator 1509 via a pipeline. The pipeline between the condensate pump and the deaerator 1509 also exchanges heat through the seventh low-temperature heater 1506, the sixth low-temperature heater 1505 and the fifth low-temperature heater 1504 in sequence. The outlet of the deaerator 1509 is connected to the feed water pump 1510 via a pipeline. The other end of the feed water pump 1510 is connected to the main steam inlet via a pipeline. The pipeline between the feed water pump 1510 and the main steam inlet also exchanges heat through the third high-temperature heater 1503, the second high-temperature heater 1502 and the first high-temperature heater 1501 in sequence.

[0031] Example 5 like Figure 1 , Figure 2 and Figure 3As shown, the high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power proposed in this embodiment includes a boiler power generation unit. In the thermal storage mode, the boiler power generation unit and the thermal storage unit are connected for heat exchange through corresponding heat exchangers; in the heat release mode, the boiler power generation unit and the heat release unit are connected for heat exchange through corresponding heat exchangers. The boiler power generation unit includes a high-pressure cylinder module, which is connected to a medium-pressure cylinder module via a shaft. The medium-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft. The boiler power generation unit also includes a boiler superheater 15, which has a main steam outlet, a main steam inlet, a reheat steam outlet, and a reheat steam inlet. The main steam outlet of the boiler superheater 15 is connected to the high-pressure cylinder module via a pipeline. The high-pressure cylinder module is connected to the first high-temperature heater 1501 and the second high-temperature heater 1502 via two pipelines respectively. A first branch pipeline is also connected to the pipeline between the high-pressure cylinder module and the second high-temperature heater 1502. The other end of the first branch pipeline is connected to the reheat steam inlet of the boiler superheater 15. The reheat steam outlet is connected to the intermediate-pressure cylinder module via a pipeline. The intermediate-pressure cylinder module includes a first outlet, a second outlet, a third outlet, and a fourth outlet. The first outlet of the intermediate-pressure cylinder is connected to... The system is equipped with a third high-temperature heater 1503, a second outlet of the intermediate-pressure cylinder connected to the inlet of the deaerator 1509 via a pipe, a third outlet of the intermediate-pressure cylinder connected to a fifth low-temperature heater 1504 via a pipe, and a fourth outlet of the intermediate-pressure cylinder connected to the inlet of the low-pressure cylinder module via a pipe. The low-pressure cylinder module also includes a first outlet, a second outlet, and a third outlet of the low-pressure cylinder. The first outlet of the low-pressure cylinder is connected to a sixth low-temperature heater 1505 via a pipe, the second outlet of the low-pressure cylinder is connected to a seventh low-temperature heater 1506 via a pipe, and the third outlet of the low-pressure cylinder is connected to a condenser 1507 via a pipe.The first high-temperature heater 1501 is connected to the second high-temperature heater 1502 via a pipeline. The second high-temperature heater 1502 is connected to the third high-temperature heater 1503 via a pipeline. The third high-temperature heater 1503 is connected to the inlet of the deaerator 1509 via a pipeline. The fifth low-temperature heater 1504 is connected to the sixth low-temperature heater 1505 via a pipeline. The sixth low-temperature heater 1505 is connected to the seventh low-temperature heater 1506 via a pipeline. The seventh low-temperature heater 1506 is connected to the air inlet of the condenser 1507 via a pipeline. The outlet of the condenser 1507 is connected to the condensate pump 1508 via a pipeline. The other end of the condensate pump 1508 is connected to the inlet of the deaerator 1509 via a pipeline. The pipeline between the condensate pump and the deaerator 1509 also exchanges heat through the seventh low-temperature heater 1506, the sixth low-temperature heater 1505 and the fifth low-temperature heater 1504 in sequence. The outlet of the deaerator 1509 is connected to the feed water pump 1510 via a pipeline. The other end of the feed water pump 1510 is connected to the main steam inlet via a pipeline. The pipeline between the feed water pump 1510 and the main steam inlet also exchanges heat through the third high-temperature heater 1503, the second high-temperature heater 1502 and the first high-temperature heater 1501 in sequence. The thermal storage unit includes a high-temperature solar salt tank 1, which is connected to a first steam-molten salt heat exchanger 5 via a pipeline. The first steam-molten salt heat exchanger 5 is connected to a second steam-molten salt heat exchanger 6 via a pipeline. The second steam-molten salt heat exchanger 6 is connected to a low-temperature solar salt pump 9 via a pipeline. The low-temperature solar salt pump 9 is connected to a low-temperature solar salt tank 2 via a pipeline. The thermal storage unit also includes a low-temperature Hitec salt tank 4, which is connected to a low-temperature Hitec salt pump 10 via a pipeline. The low-temperature Hitec salt pump 10 is connected to a phase change heat exchanger 7 via a pipeline. The phase change heat exchanger 7 is connected to a high-temperature Hitec salt tank 3 via a pipeline. The air inlet of the first steam-molten salt heat exchanger 5 is connected to the boiler via a pipeline. The main steam outlet of the superheater 15 is connected to the steam outlet of the first steam-molten salt heat exchanger 5. The outlet of the first steam-molten salt heat exchanger 5 is connected to the inlet of the phase change heat exchanger 7 through a pipe. The outlet of the phase change heat exchanger 7 is connected to a general heat exchanger 8 through a pipe. The outlet of the general heat exchanger 8 is connected to the inlet of the feed water pump 1510 through a pipe. The outlet of the feed water pump 1510 is connected to the outlet of the first high-temperature heater 1501 through a pipe. The pipe between the feed water pump 1510 and the first high-temperature heater 1501 exchanges heat through the general heat exchanger 8. The inlet of the second steam-molten salt heat exchanger 6 is connected to the reheat steam outlet of the boiler superheater 15 through a pipe. The outlet of the second steam-molten salt heat exchanger 6 is connected to the inlet of the low-pressure cylinder module through a pipe.The heat release unit includes a high-temperature solar salt tank 1, which is connected to a high-temperature solar salt pump 13 via a pipe. The high-temperature solar salt pump 13 is connected to a molten salt-feedwater evaporator 11 via a pipe. The molten salt-feedwater evaporator 11 is connected to a low-temperature solar salt tank 2 via a pipe. The inlet of the molten salt-feedwater evaporator 11 is connected to the outlet of the first high-temperature heater 1501 via a pipe, and the outlet of the molten salt-feedwater evaporator 11 is connected to the reheat steam inlet via a pipe. The heat release unit also includes a high-temperature Hitec salt tank 3, which is connected to a molten salt-feedwater heat exchanger 12 via a pipe. The molten salt-feedwater heat exchanger 12 is connected to a low-temperature Hitec salt tank 4 via a pipe. The inlet of the molten salt-feedwater heat exchanger 12 is connected to the outlet of the feedwater pump 1510 via a pipe, and the outlet of the molten salt-feedwater heat exchanger 12 is connected to the outlet of the first high-temperature heater 1501 via a pipe.

[0032] Example 6 like Figure 1 , Figure 2 and Figure 3 As shown, the method for a high- and low-parameter molten salt cascade energy storage system for peak shaving of thermal power proposed in this embodiment includes the following steps: In the thermal storage working mode, the solar salt in the low-temperature solar salt tank 2 exchanges heat through the second steam-molten salt heat exchanger 6 and the first steam-molten salt heat exchanger 5, and then flows into the high-temperature solar salt tank 1; the Hitec salt in the low-temperature Hitec salt tank 4 exchanges heat through the phase change heat exchanger 7 and then flows into the high-temperature Hitec salt tank 3. In the heat release mode, the high-temperature solar salt in the high-temperature solar salt tank 1 flows into the low-temperature solar salt tank 2 after heat exchange through the molten salt-feedwater evaporator 11; the high-temperature Hitec salt in the high-temperature Hitec salt tank 3 flows into the low-temperature Hitec salt tank 4 after heat exchange through the molten salt-feedwater heat exchanger 12.

Claims

1. A high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants, characterized in that, It includes a boiler power generation unit. In the heat storage mode, the boiler power generation unit and the heat storage unit are connected and exchange heat through a corresponding heat exchanger. In the heat release mode, the boiler power generation unit and the heat release unit are connected and exchange heat through a corresponding heat exchanger.

2. The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 1, characterized in that, The boiler power generation unit includes a high-pressure cylinder module, which is connected to a medium-pressure cylinder module via a shaft. The medium-pressure cylinder module is connected to a low-pressure cylinder module via a shaft, and the low-pressure cylinder module is connected to a generator via a shaft.

3. The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 2, characterized in that, The boiler power generation unit also includes a boiler superheater (15), which is provided with a main steam outlet, a main steam inlet, a reheat steam outlet, and a reheat steam inlet.

4. The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 3, characterized in that, The main steam outlet of the boiler superheater (15) is connected to the high-pressure cylinder module through a pipe. The high-pressure cylinder module is connected to the first high-temperature heater (1501) and the second high-temperature heater (1502) through two pipes respectively. A first branch pipe is also connected to the pipe between the high-pressure cylinder module and the second high-temperature heater (1502). The other end of the first branch pipe is connected to the reheat steam inlet of the boiler superheater (15). The reheat steam outlet is connected to the intermediate pressure cylinder module via a pipeline. The intermediate pressure cylinder module includes a first outlet, a second outlet, a third outlet, and a fourth outlet. The first outlet is connected to a third high-temperature heater (1503) via a pipeline. The second outlet is connected to the inlet of a deaerator (1509) via a pipeline. The third outlet is connected to a fifth low-temperature heater (1504) via a pipeline. The fourth outlet is connected to the inlet of the low-pressure cylinder module via a pipeline. The low-pressure cylinder module further includes a first low-pressure cylinder outlet, a second low-pressure cylinder outlet, and a third low-pressure cylinder outlet. The first low-pressure cylinder outlet is connected to a sixth cryogenic heater (1505) via a pipe, the second low-pressure cylinder outlet is connected to a seventh cryogenic heater (1506) via a pipe, and the third low-pressure cylinder outlet is connected to a condenser (1507) via a pipe.

5. The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 4, characterized in that, The first high-temperature heater (1501) is connected to the second high-temperature heater (1502) through a pipe, the second high-temperature heater (1502) is connected to the third high-temperature heater (1503) through a pipe, and the third high-temperature heater (1503) is connected to the inlet of the deaerator (1509) through a pipe; The fifth cryogenic heater (1504) is connected to the sixth cryogenic heater (1505) via a pipe, the sixth cryogenic heater (1505) is connected to the seventh cryogenic heater (1506) via a pipe, and the seventh cryogenic heater (1506) is connected to the air inlet of the condenser (1507) via a pipe. The outlet of the condenser (1507) is connected to a condensate pump (1508) via a pipe. The other end of the condensate pump (1508) is connected to the inlet of the deaerator (1509) via a pipe. The pipe between the condensate pump and the deaerator (1509) also exchanges heat through the seventh cryogenic heater (1506), the sixth cryogenic heater (1505), and the fifth cryogenic heater (1504) in sequence. The outlet of the deaerator (1509) is connected to a feed water pump (1510) via a pipeline. The other end of the feed water pump (1510) is connected to the main steam inlet via a pipeline. The pipeline between the feed water pump (1510) and the main steam inlet is also connected to a third high-temperature heater (1503), a second high-temperature heater (1502), and a first high-temperature heater (1501) for heat exchange in sequence.

6. The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 5, characterized in that, The heat storage unit includes a high-temperature solar salt tank (1), which is connected to a first steam-molten salt heat exchanger (5) via a pipe. The first steam-molten salt heat exchanger (5) is connected to a second steam-molten salt heat exchanger (6) via a pipe. The second steam-molten salt heat exchanger (6) is connected to a low-temperature solar salt pump (9) via a pipe. The low-temperature solar salt pump (9) is connected to a low-temperature solar salt tank (2) via a pipe. The thermal storage unit also includes a low-temperature Hitec salt tank (4), which is connected to a low-temperature Hitec salt pump (10) via a pipe. The low-temperature Hitec salt pump (10) is connected to a phase change heat exchanger (7) via a pipe. The phase change heat exchanger (7) is connected to a high-temperature Hitec salt tank (3) via a pipe. The inlet of the first steam-molten salt heat exchanger (5) is connected to the main steam outlet of the boiler superheater (15) through a pipe. The outlet of the first steam-molten salt heat exchanger (5) is connected to the inlet of the phase change heat exchanger (7) through a pipe. The outlet of the phase change heat exchanger (7) is connected to a common heat exchanger (8) through a pipe. The outlet of the common heat exchanger (8) is connected to the inlet of the feed water pump (1510) through a pipe. The outlet of the water pump (1510) is connected to the air outlet of the first high-temperature heater (1501) through a pipe, and the pipe between the water pump (1510) and the first high-temperature heater (1501) exchanges heat through a common heat exchanger (8). The inlet of the second steam-molten salt heat exchanger (6) is connected to the reheat steam outlet of the boiler superheater (15) via a pipe, and the outlet of the second steam-molten salt heat exchanger (6) is connected to the inlet of the low-pressure cylinder module via a pipe.

7. The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 5, characterized in that, The heat release unit includes a high-temperature solar salt tank (1), which is connected to a high-temperature solar salt pump (13) via a pipe. The high-temperature solar salt pump (13) is connected to a molten salt-feed water evaporator (11) via a pipe. The molten salt-feed water evaporator (11) is connected to a low-temperature solar salt tank (2) via a pipe. The inlet of the molten salt-feed water evaporator (11) is connected to the outlet of the first high-temperature heater (1501) through a pipe, and the outlet of the molten salt-feed water evaporator (11) is connected to the reheat steam inlet through a pipe. The heat release unit also includes a high-temperature Hitec salt tank (3), which is connected to a molten salt-feed water heat exchanger (12) via a pipe, and the molten salt-feed water heat exchanger (12) is connected to a low-temperature Hitec salt tank (4) via a pipe. The inlet of the molten salt-feed water heat exchanger (12) is connected to the outlet of the feed water pump (1510) through a pipe, and the outlet of the molten salt-feed water heat exchanger (12) is connected to the outlet of the first high-temperature heater (1501) through a pipe.

8. A heat storage and release method for a high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants, characterized in that, The high- and low-parameter molten salt cascade energy storage system for peak shaving in thermal power plants according to claim 1 comprises the following: In the thermal storage mode, the solar salt in the low-temperature solar salt tank (2) exchanges heat through the second steam-molten salt heat exchanger (6) and the first steam-molten salt heat exchanger (5), and then flows into the high-temperature solar salt tank (1); the Hitec salt in the low-temperature Hitec salt tank (4) exchanges heat through the phase change heat exchanger (7) and then flows into the high-temperature Hitec salt tank (3). In the heat release mode, the high-temperature solar salt in the high-temperature solar salt tank (1) flows into the low-temperature solar salt tank (2) after heat exchange through the molten salt-feed water evaporator (11); the high-temperature Hitec salt in the high-temperature Hitec salt tank (3) flows into the low-temperature Hitec salt tank (4) after heat exchange through the molten salt-feed water heat exchanger (12).

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