Thermal power generating unit peak regulation system and method coupled with double-medium energy storage

Abstract

The invention relates to a thermal power generating unit peak regulation system and method coupled with double-medium energy storage. The system comprises a fused salt energy storage peak regulation system and a hot water energy storage peak regulation system. The hot water energy storage peak regulation system comprises a heat storage water tank and a steam-water pipeline. A hot water outlet of the heat storage water tank is connected with an outlet of the deaerator; a hot water inlet of the heat storage water tank is connected with an outlet of the low-pressure heater; a cold water inlet of the heat storage water tank is connected with an outlet of the condensate pump, and a cold water outlet of the heat storage water tank is connected with the condenser. According to the method, fused salt energy storage peak regulation is adopted at night, and hot water energy storage peak regulation is adopted in daytime. A high-temperature heat source adopts fused salt collection, and a low-temperature heat source adopts hot water collection. The heat of a low-temperature heat source can be collected and utilized, and the heat efficiency of the unit is improved and the flexibility of the unit is improved through reasonable collocation and application of heat storage of the two media.

Description

Technical Field

[0001] This invention relates to a peak-shaving system and method for thermal power units with coupled dual-medium energy storage, belonging to the technical field of thermal power peak shaving in thermal power plants. Background Technology

[0002] With the increasing proportion of photovoltaic, wind, and hydropower in the power grid, there is an urgent need to improve the peak-shaving capacity of thermal power units. Coupled molten salt energy storage for peak shaving is a novel peak-shaving solution. It achieves the collection and utilization of thermal energy through the heat absorption / release function of molten salt.

[0003] Current coupled molten salt energy storage and peak shaving systems typically use molten salt as a medium. Molten salt operates at temperatures ranging from approximately 200℃±8℃ to 400℃±8℃, making it difficult to collect and utilize the low-temperature heat generated during power plant operation below 200℃±8℃.

[0004] Thermal power units need to store a large amount of heat at night, so molten salt is used. During the day, only intermittent heat energy is stored, and the molten salt peak-shaving system cannot play its storage role. This results in the ineffective storage of low-temperature energy during the day, causing energy waste and hindering low-carbon energy. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a peak-shaving system and method for thermal power units with coupled dual-medium energy storage. The high-temperature heat source is collected using molten salt, and the low-temperature heat source is collected using hot water. This system not only collects and utilizes heat from the low-temperature heat source but also improves the unit's thermal efficiency and increases its flexibility. The specific technical solution is as follows: A peak-shaving system for thermal power units coupled with dual-medium energy storage includes a molten salt energy storage peak-shaving system and a hot water energy storage peak-shaving system; The molten salt energy storage peak-shaving system includes: a hot salt tank (1), a cold salt tank (2), a first molten salt heat exchanger (7), a second molten salt heat exchanger (8), a third molten salt heat exchanger (9), and a steam ejector (6); the cold salt tank (2) is connected to the hot salt tank (1) through the first molten salt heat exchanger (7) and the second molten salt heat exchanger (8); the hot salt tank (1) is connected to the cold salt tank (2) through the third molten salt heat exchanger (9); the steam outlets of the first molten salt heat exchanger (7) and the second molten salt heat exchanger (8) are connected to the steam ejector (6); The hot water storage peak-shaving system includes: a hot water storage tank (20) and steam and water pipelines; The hot water outlet (2001) of the hot water storage tank (20) is connected to the outlet of the deaerator (15) through a steam-water pipeline; the hot water inlet (2002) of the hot water storage tank (20) is connected to the outlet of the low-pressure heater (14) through a steam-water pipeline; the cold water inlet (2004) of the hot water storage tank (20) is connected to the outlet of the condensate pump (13) through a steam-water pipeline; and the cold water outlet (2003) of the hot water storage tank is connected to the condenser (12) through a steam-water pipeline.

[0006] Furthermore, the hot water storage peak-shaving system also includes a high-pressure cylinder (3), a medium-pressure cylinder (4), a low-pressure cylinder (5), and a low-pressure heater (14). The outlet of the condenser (12) is connected to the inlet of the condensate pump (13), the outlet of the condensate pump (13) is also connected to the inlet of the low-pressure heater (14), the outlet of the low-pressure heater (14) is connected to the circulating water pump (28), and the outlet of the circulating water pump (28) is connected to the high-pressure heater (16).

[0007] Furthermore, the low-pressure heater (14) includes a series of low-pressure heaters No. 4 (24), No. 5 (25), No. 6 (26), and No. 7 (27). The water vapor from the low-pressure cylinder (5) is condensed into water in the condenser (12), and the water is then transported to the low-pressure heater (14) by the condensate pump (13).

[0008] Furthermore, the molten salt inlet (701) of the first molten salt heat exchanger (7) is connected to the outlet of the cold salt tank (2) through a molten salt pipe, the molten salt outlet (702) is connected to the inlet of the hot salt tank (1) through a molten salt pipe, the steam inlet (704) of the first molten salt heat exchanger (7) is connected to the outlet of the superheater (10) through a steam-water pipe, and the steam outlet (703) is connected to the first inlet (601) of the steam ejector (6) through a steam-water pipe; The molten salt inlet (801) of the second molten salt heat exchanger (8) is connected to the outlet of the cold salt tank (2) through a molten salt pipe, the molten salt outlet (802) is connected to the inlet of the hot salt tank (1) through a molten salt pipe, the steam inlet (804) of the second molten salt heat exchanger (8) is connected to the outlet of the reheater (11) through a steam-water pipe, and the steam outlet (803) is connected to the second inlet (602) of the steam ejector (6) through a steam-water pipe. The molten salt inlet (901) of the third molten salt heat exchanger (9) is connected to the outlet of the hot salt tank (1) through a molten salt pipe, the molten salt outlet (902) is connected to the inlet of the cold salt tank (2) through a molten salt pipe, the steam-water inlet (903) is connected to the outlet of the high-pressure heater (16) through a steam-water pipe, and the steam-water outlet (904) is connected to the steam drum (18) through a steam-water pipe. The steam ejector outlet (603) of the steam ejector (6) is connected to the inlet of the reheater (11) via a steam-water pipe.

[0009] Furthermore, the high-pressure heater (16) includes a No. 1 high-pressure heater (21), a No. 2 high-pressure heater (22), and a No. 3 high-pressure heater (23) connected in series. Steam from the high-pressure heater (16) is delivered to the No. 1 high-pressure heater (21) and the No. 2 high-pressure heater (22), and steam from the intermediate-pressure cylinder (4) is delivered to the No. 3 high-pressure heater (23). After being preheated in the high-pressure heater (16), the steam is delivered to the economizer (17).

[0010] Furthermore, both the molten salt pipeline and the steam-water pipeline are equipped with valves, temperature sensors, pressure sensors, and flow sensors.

[0011] Furthermore, the hot salt tank (1), cold salt tank (2) and hot water storage tank (20) are all equipped with valves, temperature sensors, pressure sensors and liquid level sensors.

[0012] The peak-shaving method based on the above-mentioned coupled dual-medium energy storage thermal power unit peak-shaving system includes the following steps: At night, a molten salt energy storage peak-shaving system is used for peak shaving; During the day, a hot water storage peak-shaving system is used for peak shaving.

[0013] Furthermore, the specific process of molten salt energy storage for peak shaving at night is as follows: When the unit load drops to 40% MCR (boiler full load), the molten salt energy storage peak-shaving system is started: First, the steam inlet valve (705) of the first molten salt heat exchanger is opened, and the first molten salt heat exchanger (7) is started. High-temperature superheated steam of 535℃±8℃ flows out from the superheater (10) and flows into the first molten salt heat exchanger (7) from the steam inlet (704). Low-temperature molten salt of 298℃±8℃ flows out from the cold salt tank (2) and flows into the first molten salt heat exchanger (7) from the molten salt inlet (701). In the first molten salt heat exchanger (7), the molten salt absorbs heat and the steam releases heat. After heat exchange, low-temperature steam of 311℃±8℃ flows out from the steam outlet (703) of the first molten salt heat exchanger and flows to the first inlet (601) of the steam ejector. High-temperature molten salt of 430℃±8℃ flows out from the molten salt outlet (702) of the first molten salt heat exchanger and flows to the hot salt tank (1). Then, the steam inlet valve (805) of the second molten salt heat exchanger is opened, and the second molten salt heat exchanger (8) is started. High-temperature reheat steam at 525℃±8℃ flows out from the reheater (11) and flows into the second molten salt heat exchanger (8) through the steam inlet (804). Low-temperature molten salt at 298℃±8℃ flows out from the cold salt tank (2) and flows into the second molten salt heat exchanger (8) through the molten salt inlet (801). In the second molten salt heat exchanger (8), the molten salt absorbs heat and the steam releases heat. After heat exchange, low-temperature steam at 309℃±8℃ flows out from the steam outlet (803) of the second molten salt heat exchanger and flows to the second inlet (602) of the steam ejector. High-temperature molten salt at 430℃±8℃ flows out from the molten salt outlet (802) of the second molten salt heat exchanger and flows to the hot salt tank (1). The first molten salt heat exchanger (7) and the second molten salt heat exchanger (8) work simultaneously to regulate the outlet temperature of the steam ejector (6). The first molten salt heat exchanger (7) and the second molten salt heat exchanger (8) are for heating molten salt and storing energy.

[0014] In the steam ejector (6), steam from the first molten salt heat exchanger (7) is mixed with steam from the second molten salt heat exchanger (8), and the mixed steam flows into the reheater (11) through the steam ejector outlet (603). In the early morning, the unit increases its load, closes the steam inlet valve (705) of the first molten salt heat exchanger and the steam inlet valve (805) of the second molten salt heat exchanger, and stops molten salt energy storage. When the unit load rises to over 90%, start the molten salt heat release: open the steam-water inlet valve (905) of the third molten salt heat exchanger, start the third molten salt heat exchanger (9), the 270℃±8℃ low temperature steam-water mixture flows out from the No. 1 high pressure heater (21), and flows into the third molten salt heat exchanger (9) from the steam-water inlet (903). The 430℃±8℃ high temperature molten salt flows out from the hot salt tank (1), and flows into the third molten salt heat exchanger (9) from the molten salt inlet (901). In the third molten salt heat exchanger (9), the molten salt releases heat and the steam-water absorbs heat. After the heat exchange, the 330℃±8℃ high temperature steam-water mixture flows out from the steam-water outlet (904) of the third molten salt heat exchanger and flows into the steam drum (18). The 298℃±8℃ low temperature molten salt flows out from the molten salt outlet (902) of the third molten salt heat exchanger and flows to the cold salt tank (2). The function of the third molten salt heat exchanger (9) is to release heat, releasing the stored heat in the morning.

[0015] Furthermore, the specific process of daytime hot water energy storage for peak shaving is as follows: When the unit reduces load, the hot water storage peak-shaving system is started: at this time, the water supply is reduced, the water level of the deaerator (15) is kept unchanged, the high temperature inlet valve (2006) and low temperature outlet valve (2007) of the hot water storage tank are opened, and the 140℃±8℃ high temperature hot water flows into the hot water storage tank (20) from the No. 4 low pressure heater (24), and the original 40℃±8℃ low temperature water in the tank is discharged into the condenser (12). When the unit increases its load, hot water release is started: at this time, the water supply is increased, the water level of the deaerator (15) is kept unchanged, the low temperature inlet valve (2008) and high temperature outlet valve (2005) of the hot water storage tank are opened, and the low temperature cold water of 40℃±8℃ flows into the hot water storage tank (20) from the condensate pump (13), and the original high temperature hot water of 140℃±8℃ in the tank is discharged to the deaerator outlet.

[0016] The beneficial effects of this invention are: This invention employs dual-medium energy storage: molten salt for high-temperature heat sources and hot water for low-temperature heat sources; molten salt is used for long-term energy storage, while hot water is used for short-term energy storage; and, based on minimizing heat loss, the heat collection and utilization of the peak-shaving system are designed in depth. Through the rational combination of the two media for heat storage, the thermal efficiency of the unit is improved and the flexibility of the unit is increased. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of a peak-shaving system for a coupled dual-medium energy storage thermal power unit according to the present invention; Figure 2 This is a process flow diagram of a molten salt energy storage peak-shaving system; Figure 3 This is a process flow diagram of a hot water energy storage peak-shaving system.

[0018] List of reference numerals in the attached diagram: 1-Hot brine tank; 2-Cold brine tank; 3-High-pressure cylinder; 4-Medium-pressure cylinder; 5-Low-pressure cylinder; 6-Steam ejector; 7-First molten salt heat exchanger; 8-Second molten salt heat exchanger; 9-Third molten salt heat exchanger; 10-Boiler superheater; 11-Boiler reheater; 12-Condenser; 13-Condensate pump; 14-Low-pressure heater; 15-Deaerator; 16-High-pressure heater; 17-Economizer; 18-Steam drum; 19-Generator; 20-Hot water storage tank; 21-No. 1 high-pressure... Heaters; 22-2 High-pressure heater; 23-3 High-pressure heater; 24-4 Low-pressure heater; 25-5 Low-pressure heater; 26-6 Low-pressure heater; 27-7 Low-pressure heater; 28 Circulating water pump; 601 First inlet of steam ejector; 602 Second inlet of steam ejector; 603 Outlet of steam ejector; 701 Molten salt inlet of first molten salt heat exchanger; 702 Molten salt outlet of first molten salt heat exchanger; 703 Steam outlet of first molten salt heat exchanger Steam outlet; 704-Steam inlet of the first molten salt heat exchanger; 705-Steam inlet valve of the first molten salt heat exchanger; 801-Molten salt inlet of the second molten salt heat exchanger; 802-Molten salt outlet of the second molten salt heat exchanger; 803-Steam outlet of the second molten salt heat exchanger; 804-Steam inlet of the second molten salt heat exchanger; 805-Steam inlet valve of the second molten salt heat exchanger; 901-Molten salt inlet of the third molten salt heat exchanger; 902-Molten salt outlet of the third molten salt heat exchanger; 903-Third molten salt heat exchanger 904 - Steam / water inlet; 905 - Steam / water outlet of the third molten salt heat exchanger; 2001 - Hot water outlet of the hot water storage tank; 2002 - Hot water inlet of the hot water storage tank; 2003 - Cold water outlet of the hot water storage tank; 2004 - Cold water inlet of the hot water storage tank; 2005 - High-temperature outlet valve of the hot water storage tank; 2006 - High-temperature inlet valve of the hot water storage tank; 2007 - Low-temperature outlet valve of the hot water storage tank; 2008 - Low-temperature inlet valve of the hot water storage tank. Detailed Implementation

[0019] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0020] Combined with appendix Figure 1-3 It can be seen that the peak-shaving system of this coupled dual-medium energy storage thermal power unit includes a molten salt energy storage peak-shaving system and a hot water energy storage peak-shaving system.

[0021] The molten salt energy storage and peak shaving system includes a hot salt tank 1, a cold salt tank 2, a first molten salt heat exchanger 7, a second molten salt heat exchanger 8, a third molten salt heat exchanger 9, and a steam ejector 6. These components are connected into a system through pipelines.

[0022] In the first molten salt heat exchanger 7, the molten salt inlet 701 is connected to the outlet of the cold salt tank 2 via a molten salt pipeline, and the molten salt outlet 702 is connected to the inlet of the hot salt tank 1 via a steam-water pipeline; the steam inlet 704 is connected to the outlet of the superheater 10 via a steam-water pipeline, and the steam outlet 703 is connected to the first inlet 601 of the steam ejector. In the second molten salt heat exchanger 8, the molten salt inlet 801 is connected to the outlet of the cold salt tank 2 via a molten salt pipeline, and the molten salt outlet 802 is connected to the inlet of the hot salt tank 1 via a steam-water pipeline; the steam inlet 804 is connected to the outlet of the reheater 11 via a steam-water pipeline, and the steam outlet 803 is connected to the second inlet 602 of the steam ejector. In the third molten salt heat exchanger 9, the molten salt inlet 901 is connected to the outlet of the hot salt tank 1 via a molten salt pipeline, and the molten salt outlet 902 is connected to the inlet of the cold salt tank 2 via a steam-water pipeline; the steam-water inlet 903 is connected to the outlet of the high-pressure heater 16 via a steam-water pipeline, and the steam-water outlet 904 is connected to the steam drum 18. In the steam ejector 6, the steam ejector outlet 603 is connected to the inlet of the reheater 11 via a steam-water pipe.

[0023] The molten salt energy storage and peak shaving system also includes a high-pressure cylinder 3 and a medium-pressure cylinder 4 shared with the hot water energy storage and peak shaving system. Part of the steam from the boiler superheater 10 is pressurized by the high-pressure cylinder 3 and the high-pressure heater 16, and then recirculated into the inlet of the economizer 10 or the steam-water inlet 903 of the third molten salt heat exchanger 9.

[0024] The hot water storage peak-shaving system includes a hot water storage tank 20 and steam-water pipelines. Through the steam-water pipelines, the hot water outlet 2001 of the hot water storage tank is connected to the outlet of the deaerator 15; the hot water inlet 2002 of the hot water storage tank is connected to the outlet of the low-pressure heater 14; the cold water inlet 2004 of the hot water storage tank is connected to the outlet of the condensate pump 13; and the cold water outlet 2003 of the hot water storage tank is connected to the condenser 12.

[0025] The hot water storage and peak-shaving system also includes a high-pressure cylinder 3, a medium-pressure cylinder 4, a low-pressure cylinder 5, and a low-pressure heater 14. The outlet of the condenser 12 is connected to the inlet of the condensate pump 13, and the outlet of the condensate pump 13 is also connected to the inlet of the low-pressure heater 14. The outlet of the low-pressure heater 14 is connected to the circulating water pump 28, and the outlet of the circulating water pump 28 is connected to the high-pressure heater 16. Steam thermal energy is converted into mechanical energy through the high-pressure cylinder 3, medium-pressure cylinder 4, and low-pressure cylinder 5, and the mechanical energy is converted into electrical energy through the generator 19.

[0026] The low-pressure heater 14 includes a series of low-pressure heaters 24 (No. 4), 25 (No. 5), 26 (No. 6), and 27 (No. 7) connected in series. Water vapor from the low-pressure cylinder 5 is condensed into water in the condenser 12, and the water is then transported to the low-pressure heater 14 by the condensate pump 13.

[0027] The high-pressure heater 16 includes a No. 1 high-pressure heater 21, a No. 2 high-pressure heater 22, and a No. 3 high-pressure heater 23 connected in series. Steam from the high-pressure heater 16 is delivered to the No. 1 high-pressure heater 21 and the No. 2 high-pressure heater 22, and steam from the intermediate-pressure cylinder 4 is delivered to the No. 3 high-pressure heater 23. After being preheated in the high-pressure heater 16, the steam is delivered to the economizer 17.

[0028] Valves, temperature sensors, pressure sensors, level sensors, and other instrumentation and control equipment are installed on hot salt tanks, cold salt tanks, and hot water storage tanks.

[0029] Valves, temperature sensors, pressure sensors, flow sensors, and other instrumentation and control equipment are installed on molten salt pipelines and steam-water pipelines.

[0030] Molten salt energy storage is used for peak shaving at night, while hot water energy storage is used during the day. The specific operation mode is as follows: At night, the unit has a long period of stable low load and uses molten salt energy storage for peak shaving.

[0031] When the unit load drops to 40% MCR (MCR represents full boiler load), molten salt energy storage is activated. First, the steam inlet valve 705 of the first molten salt heat exchanger is opened, starting the first molten salt heat exchanger 7. High-temperature superheated steam at 535℃±8℃ flows out from superheater 10 and into the first molten salt heat exchanger 7 through steam inlet 704. Low-temperature molten salt at 298℃±8℃ flows out from cold salt tank 2 and into the first molten salt heat exchanger 7 through molten salt inlet 701. In the first molten salt heat exchanger 7, the molten salt absorbs heat, and the steam releases heat. After heat exchange, low-temperature steam at 311℃±8℃ flows out from the steam outlet 703 of the first molten salt heat exchanger and into the first inlet 601 of the steam ejector. High-temperature molten salt at 430℃±8℃ flows out from the molten salt outlet 702 of the first molten salt heat exchanger and into hot salt tank 1.

[0032] Then, the steam inlet valve 805 of the second molten salt heat exchanger is opened, and the second molten salt heat exchanger 8 is started. High-temperature reheat steam at 525℃±8℃ flows out of the reheater 11 and into the second molten salt heat exchanger 8 through the steam inlet 804. Low-temperature molten salt at 298℃±8℃ flows out of the cold salt tank 2 and into the second molten salt heat exchanger 8 through the molten salt inlet 801. In the second molten salt heat exchanger 8, the molten salt absorbs heat, and the steam releases heat. After heat exchange, low-temperature steam at 309℃±8℃ flows out of the steam outlet 803 of the second molten salt heat exchanger and into the second inlet 602 of the steam ejector. High-temperature molten salt at 430℃±8℃ flows out of the molten salt outlet 802 of the second molten salt heat exchanger and into the hot salt tank 1.

[0033] In the steam ejector 6, steam from the first molten salt heat exchanger 7 is mixed with steam from the second molten salt heat exchanger 8, and the mixed steam flows into the reheater 11 through the steam ejector outlet 603.

[0034] In the early morning, the unit increases its load, closes the steam inlet valve 705 of the first molten salt heat exchanger and the steam inlet valve 805 of the second molten salt heat exchanger, and stops molten salt energy storage.

[0035] When the unit load rises above 90%, molten salt heat release is initiated. The steam-water inlet valve 905 of the third molten salt heat exchanger is opened, and the third molten salt heat exchanger 9 is started. A low-temperature steam-water mixture of 270℃±8℃ flows out from the No. 1 high-pressure heater 21 and into the third molten salt heat exchanger 9 through the steam-water inlet 903. High-temperature molten salt of 430℃±8℃ flows out from the hot salt tank 1 and into the third molten salt heat exchanger 9 through the molten salt inlet 901. In the third molten salt heat exchanger 9, the molten salt releases heat, and the steam-water mixture absorbs heat. After heat exchange, the high-temperature steam-water mixture at 330℃±8℃ flows out from the steam-water outlet 904 of the third molten salt heat exchanger and into the economizer 17 (the economizer 17 uses the waste heat of the low-temperature flue gas at the tail of the boiler to preheat the feedwater entering the boiler), and then flows from the economizer 17 into the steam drum 18. The low-temperature molten salt at 298℃±8℃ flows out from the molten salt outlet 902 of the third molten salt heat exchanger and into the cold salt tank 2.

[0036] During the day, in order to regulate the peak load of photovoltaic and hydropower, the power generation load will fluctuate for a short time, and the unit uses hot water energy storage for peak regulation.

[0037] When the unit reduces load, the hot water storage is activated. At this time, the water supply is reduced, the water level of the deaerator 15 is kept constant, the high temperature inlet valve 2006 and the low temperature outlet valve 2007 of the hot water storage tank are opened, allowing the 140℃±8℃ high temperature hot water to flow from the No. 4 low pressure heater 24 into the hot water storage tank 20, and the original 40℃±8℃ low temperature water in the tank is discharged into the condenser 12.

[0038] When the unit increases its load, hot water release is initiated. At this time, the water supply is increased, the water level in the deaerator 15 remains unchanged, and the low-temperature inlet valve 2008 and high-temperature outlet valve 2005 of the hot water storage tank are opened, allowing 40℃±8℃ low-temperature cold water to flow from the condensate pump 13 into the hot water storage tank 20, and discharging the original 140℃±8℃ high-temperature hot water in the tank to the deaerator outlet.

[0039] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein.

[0040] The meaning of "and / or" as used in this application includes situations where each exists alone or both exist simultaneously.

[0041] The term "connection" as used in this application can mean a direct connection between components or an indirect connection between components through other components.

[0042] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A peak-shaving system for thermal power units coupled with dual-medium energy storage, characterized in that, This includes molten salt energy storage peak-shaving systems and hot water energy storage peak-shaving systems; The molten salt energy storage peak-shaving system includes: a hot salt tank (1), a cold salt tank (2), a first molten salt heat exchanger (7), a second molten salt heat exchanger (8), a third molten salt heat exchanger (9), and a steam ejector (6); the cold salt tank (2) is connected to the hot salt tank (1) through the first molten salt heat exchanger (7) and the second molten salt heat exchanger (8); the hot salt tank (1) is connected to the cold salt tank (2) through the third molten salt heat exchanger (9); the steam outlets of the first molten salt heat exchanger (7) and the second molten salt heat exchanger (8) are connected to the steam ejector (6); The hot water storage and peak-shaving system includes: a hot water storage tank (20) and steam and water pipelines; The hot water outlet (2001) of the hot water storage tank (20) is connected to the outlet of the deaerator (15) through a steam-water pipeline; the hot water inlet (2002) of the hot water storage tank (20) is connected to the outlet of the low-pressure heater (14) through a steam-water pipeline; the cold water inlet (2004) of the hot water storage tank (20) is connected to the outlet of the condensate pump (13) through a steam-water pipeline; and the cold water outlet (2003) of the hot water storage tank is connected to the condenser (12) through a steam-water pipeline.

2. The peak-shaving system for thermal power units with coupled dual-medium energy storage according to claim 1, characterized in that, The hot water energy storage peak shaving system also includes a medium-pressure cylinder (4), a low-pressure cylinder (5) and a low-pressure heater (14). The outlet of the condenser (12) is connected to the inlet of the condensate pump (13). The outlet of the condensate pump (13) is also connected to the inlet of the low-pressure heater (14). The outlet of the low-pressure heater (14) is connected to the circulating water pump (28). The outlet of the circulating water pump (28) is connected to the high-pressure heater (16).

3. The peak-shaving system for thermal power units with coupled dual-medium energy storage according to claim 1, characterized in that, The low-pressure heater (14) includes a series of low-pressure heaters No. 4 (24), No. 5 (25), No. 6 (26), and No. 7 (27). Water vapor from the low-pressure cylinder (5) is condensed into water in the condenser (12), and the water is then transported to the low-pressure heater (14) by the condensate pump (13).

4. The peak-shaving system for thermal power units with coupled dual-medium energy storage according to claim 1, characterized in that, The molten salt inlet (701) of the first molten salt heat exchanger (7) is connected to the outlet of the cold salt tank (2) through a molten salt pipe, the molten salt outlet (702) is connected to the inlet of the hot salt tank (1) through a molten salt pipe, the steam inlet (704) of the first molten salt heat exchanger (7) is connected to the outlet of the superheater (10) through a steam-water pipe, and the steam outlet (703) is connected to the first inlet (601) of the steam ejector (6) through a steam-water pipe; The molten salt inlet (801) of the second molten salt heat exchanger (8) is connected to the outlet of the cold salt tank (2) through a molten salt pipe, the molten salt outlet (802) is connected to the inlet of the hot salt tank (1) through a molten salt pipe, the steam inlet (804) of the second molten salt heat exchanger (8) is connected to the outlet of the reheater (11) through a steam-water pipe, and the steam outlet (803) is connected to the second inlet (602) of the steam ejector (6) through a steam-water pipe; The molten salt inlet (901) of the third molten salt heat exchanger (9) is connected to the outlet of the hot salt tank (1) through a molten salt pipe, the molten salt outlet (902) is connected to the inlet of the cold salt tank (2) through a molten salt pipe, the steam-water inlet (903) is connected to the outlet of the high-pressure heater (16) through a steam-water pipe, and the steam-water outlet (904) is connected to the steam drum (18) through a steam-water pipe. The steam ejector outlet (603) of the steam ejector (6) is connected to the inlet of the reheater (11) via a steam-water pipe.

5. The peak-shaving system for thermal power units with coupled dual-medium energy storage according to claim 1, characterized in that, The high-pressure heater (16) includes a No. 1 high-pressure heater (21), a No. 2 high-pressure heater (22), and a No. 3 high-pressure heater (23) connected in series. Steam from the high-pressure heater (16) is delivered to the No. 1 high-pressure heater (21) and the No. 2 high-pressure heater (22), and steam from the intermediate-pressure cylinder (4) is delivered to the No. 3 high-pressure heater (23). After being preheated in the high-pressure heater (16), the steam is delivered to the economizer (17).

6. The peak-shaving system for thermal power units with coupled dual-medium energy storage according to claim 1, characterized in that, Both the molten salt pipeline and the steam-water pipeline are equipped with valves, temperature sensors, pressure sensors, and flow sensors.

7. The peak-shaving system for thermal power units with coupled dual-medium energy storage according to claim 1, characterized in that, The hot salt tank (1), cold salt tank (2) and hot water storage tank (20) are all equipped with valves, temperature sensors, pressure sensors and liquid level sensors.

8. A peak-shaving method for a thermal power unit peak-shaving system with coupled dual-medium energy storage as described in any one of claims 1-7, characterized in that, Includes the following steps: At night, a molten salt energy storage peak-shaving system is used for peak shaving; During the day, a hot water storage peak-shaving system is used for peak shaving.

9. The peak-shaving method according to claim 8, characterized in that, The specific process of using a molten salt energy storage peak-shaving system for nighttime peak shaving is as follows: When the unit load drops to 40% MCR (boiler full load), start the molten salt energy storage peak shaving system: first, open the steam inlet valve (705) of the first molten salt heat exchanger, start the first molten salt heat exchanger (7), 535℃±8℃ high temperature superheated steam flows out from the superheater (10) and flows into the first molten salt heat exchanger (7) from the steam inlet (704) of the first molten salt heat exchanger, 298℃±8℃ low temperature molten salt flows out from the cold salt tank (2) and flows into the first molten salt heat exchanger (7) from the molten salt inlet (701) of the first molten salt heat exchanger. In the first molten salt heat exchanger (7), the molten salt absorbs heat and the steam releases heat; After heat exchange, low-temperature steam at 311℃±8℃ flows out from the steam outlet (703) of the first molten salt heat exchanger and flows to the first inlet (601) of the steam ejector, while high-temperature molten salt at 430℃±8℃ flows out from the molten salt outlet (702) of the first molten salt heat exchanger and flows to the hot salt tank (1). Then, the steam inlet valve (805) of the second molten salt heat exchanger is opened, and the second molten salt heat exchanger (8) is started. High-temperature reheat steam of 525℃±8℃ flows out from the reheater (11) and flows into the second molten salt heat exchanger (8) through the steam inlet (804). Low-temperature molten salt of 298℃±8℃ flows out from the cold salt tank (2) and flows into the second molten salt heat exchanger (8) through the molten salt inlet (801). In the second molten salt heat exchanger (8), the molten salt absorbs heat and the steam releases heat. After heat exchange, low-temperature steam of 309℃±8℃ flows out from the steam outlet (803) of the second molten salt heat exchanger and flows to the second inlet (602) of the steam ejector. High-temperature molten salt of 430℃±8℃ flows out from the molten salt outlet (802) of the second molten salt heat exchanger and flows to the hot salt tank (1). In the steam ejector (6), steam from the first molten salt heat exchanger (7) is mixed with steam from the second molten salt heat exchanger (8), and the mixed steam flows into the reheater (11) through the steam ejector outlet (603). In the early morning, the unit increases its load, closes the steam inlet valve (705) of the first molten salt heat exchanger and the steam inlet valve (805) of the second molten salt heat exchanger, and stops molten salt energy storage. When the unit load rises to over 90%, start the molten salt heat release: open the steam-water inlet valve (905) of the third molten salt heat exchanger, start the third molten salt heat exchanger (9), the 270℃±8℃ low temperature steam-water mixture flows out from the No. 1 high pressure heater (21), and flows into the third molten salt heat exchanger (9) from the steam-water inlet (903). The 430℃±8℃ high temperature molten salt flows out from the hot salt tank (1), and flows into the third molten salt heat exchanger (9) from the molten salt inlet (901). In the third molten salt heat exchanger (9), the molten salt releases heat and the steam-water absorbs heat. After the heat exchange, the 330℃±8℃ high temperature steam-water mixture flows out from the steam-water outlet (904) of the third molten salt heat exchanger and flows into the steam drum (18). The 298℃±8℃ low temperature molten salt flows out from the molten salt outlet (902) of the third molten salt heat exchanger and flows to the cold salt tank (2).

10. The peak-shaving method according to claim 9, characterized in that, The specific process of peak shaving in the daytime hot water storage peak shaving system is as follows: When the unit reduces load, the hot water storage peak-shaving system is started: at this time, the water supply is reduced, the water level of the deaerator (15) is kept unchanged, the high temperature inlet valve (2006) and low temperature outlet valve (2007) of the hot water storage tank are opened, and the 140℃±8℃ high temperature hot water flows into the hot water storage tank (20) from the No. 4 low pressure heater (24), and the original 40℃±8℃ low temperature water in the tank is discharged into the condenser (12). When the unit increases its load, hot water release is started: at this time, the water supply is increased, the water level of the deaerator (15) is kept unchanged, the low temperature inlet valve (2008) and high temperature outlet valve (2005) of the hot water storage tank are opened, and the low temperature cold water of 40℃±8℃ flows into the hot water storage tank (20) from the condensate pump (13), and the original high temperature hot water of 140℃±8℃ in the tank is discharged to the deaerator outlet.

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