Peak shaving system for thermal power generating unit coupling fused salt heat storage

Abstract

The utility model provides a peak shaving system for thermal power generating unit coupling fused salt heat storage, and belongs to the technical field of power generation and heat supply and storage. Comprising a thermal power generating unit used for heating feed water to generate superheated steam, heating low-temperature steam to form reheated steam, generating power and forming condensed water; the fused salt heat storage and release device is connected with a superheated steam outlet of the thermal power generating unit and used for heating the cold fused salt through superheated steam to form hot fused salt, storing the hot fused salt and heating part of feed water of the thermal power generating unit into low-temperature steam through the hot fused salt; the preheating device is connected with a steam outlet of the fused salt heat storage and release device and used for heating condensed water through steam output by the fused salt heat storage and release device, and the heated condensed water passes through a deaerator of the thermal power generating unit to form feed water; and the heat user is connected with a steam outlet of the fused salt heat storage and release device and used for utilizing the steam output by the fused salt heat storage and release device. The device is simple in structure, can realize flexible peak regulation of the thermal power generating unit, ensures the operation efficiency of the unit, and improves the utilization rate of energy.

Description

Technical Field

[0001] The utility model relates to the technical field of power generation and heat storage, and in particular to a peak regulation system of a thermal power unit coupled with molten salt heat storage. Background Art

[0002] Due to growing energy demand and heightened environmental awareness, thermal power generation coupled with thermal energy storage has attracted widespread attention as a peak-shaving technology designed to adapt to the random fluctuations of wind and solar power generation and ensure the stability and reliability of power systems. Traditional thermal power generation coupled with thermal energy storage systems have limitations in terms of flexible peak-shaving. To improve the efficient utilization and storage of thermal energy, system optimization and improvements are necessary.

[0003] At present, when the power plant's units are rapidly increasing their load, the fuel supply cannot meet the requirements of the load increase rate, resulting in the boiler being unable to quickly generate enough incremental steam. To solve this problem, it is proposed to use a molten salt heat storage and release device to store heat during the low power demand period in molten salt, and then generate steam through the molten salt heat storage and release device during the rapid load increase phase, and then enter the steam turbine to increase power. However, the steam temperature generated by the existing molten salt heat storage and release device is lower than the steam temperature generated by the boiler. After mixing with superheated steam or reheated steam, it reduces the turbine inlet steam temperature and affects the unit efficiency. In addition, cogeneration of heat and power in power plants is a relatively more economical method, but the use of main steam to directly supply heat to heat users will have a certain impact on the operating load of the steam turbine, resulting in energy waste. Utility Model Content

[0004] The purpose of the present invention is to provide a peak-shaving system for thermal power units coupled with molten salt heat storage. This system addresses the problem of steam generated by existing molten salt heat storage and release devices being lower in temperature than the steam generated by the boiler. This, when mixed with superheated or reheated steam, reduces the turbine inlet temperature, impacting unit efficiency. Furthermore, while cogeneration of heat and power in power plants offers relatively high economic benefits, the direct use of main steam to heat users can impact turbine operating loads and lead to energy waste.

[0005] In order to achieve the above objectives, the present invention provides a peak-shaving system for a thermal power unit coupled with molten salt heat storage, the system comprising:

[0006] Thermal power units, used to heat feed water to generate superheated steam, heat low-temperature steam to form reheated steam, and use superheated steam and reheated steam to generate electricity and form condensate;

[0007] A molten salt heat storage and release device is connected to the superheated steam outlet of the thermal power unit. Hot steam enters the molten salt heat storage and release device to heat the cold molten salt stored therein to form hot molten salt and store it. The formed hot molten salt can heat part of the feed water of the thermal power unit into low-temperature steam and transport it to the thermal power unit;

[0008] a preheating device connected to the steam outlet of the molten salt heat storage and release device, for heating condensate with the steam output by the molten salt heat storage and release device, wherein the heated condensate passes through the deaerator of the thermal power unit to form feed water;

[0009] A heat user is connected to the steam outlet of the molten salt heat storage and release device, and is used to utilize the steam output by the molten salt heat storage and release device, and to transport the condensed water generated in the process of utilizing the steam to the thermal power unit;

[0010] The steam outlets of the preheating device and the heat user are connected to the steam inlet of the condenser of the thermal power unit.

[0011] Optionally, the thermal power unit includes:

[0012] Superheater, reheater, high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, and the condenser, condensate pump, low-pressure heater group, deaerator, feedwater pump and high-pressure heater group connected in sequence;

[0013] The water feed inlet of the superheater is connected to the water feed outlet of the high-pressure heater group, and the steam outlet of the superheater is connected to the steam inlet of the high-pressure cylinder;

[0014] The steam inlet of the reheater is connected to the steam outlet of the high-pressure cylinder, the steam outlet of the reheater is connected to the steam inlet of the intermediate-pressure cylinder, the steam outlet of the intermediate-pressure cylinder is connected to the steam inlet of the low-pressure cylinder, and the steam outlet of the low-pressure cylinder is connected to the steam inlet of the condenser.

[0015] Optionally, the low-pressure heater group includes a plurality of low-pressure heaters connected in series;

[0016] The high-voltage heater group includes a plurality of high-voltage heaters connected in series.

[0017] Optionally, the molten salt heat storage and release device includes:

[0018] Hot tanks, used to store hot molten salt;

[0019] Cold tanks for storing cold molten salt;

[0020] A first steam condenser and a second steam condenser are used to heat molten salt using superheated steam, wherein the steam inlets of the first steam condenser and the second steam condenser are both connected to the steam outlet of the superheater, the steam outlet of the first steam condenser is connected to the steam inlet of the preheating device, and the steam outlet of the second steam condenser is connected to the heat user, the cold molten salt inlets of the first steam condenser and the second steam condenser are both connected to the cold tank, and the hot molten salt outlets of the first steam condenser and the second steam condenser are both connected to the hot tank;

[0021] The feedwater heater is used to heat the feedwater into low-temperature steam using hot molten salt. The hot molten salt inlet of the feedwater heater is connected to the hot tank, the cold molten salt outlet of the feedwater heater is connected to the cold tank, the feedwater inlet of the feedwater heater is connected to the feedwater pump outlet, and the steam outlet of the feedwater heater is connected to the steam inlet of the reheater.

[0022] A hot salt driven pump is provided between the feed water heater and the hot tank;

[0023] A cold salt driving pump is provided between the first steam condenser and the cold tank, and between the second steam condenser and the cold tank.

[0024] Optionally, a first switch valve is provided between the feed water heater and the cold tank; a second switch valve is provided between the first steam condenser and the hot tank; and a third switch valve is provided between the second steam condenser and the hot tank.

[0025] Optionally, a first steam control valve is provided between the superheater and the first steam condenser; and a second steam control valve is provided between the superheater and the second steam condenser.

[0026] Optionally, a fourth steam condenser is provided between the second steam condenser and the heat user.

[0027] Optionally, the preheating device includes:

[0028] The third steam condenser is used to heat the condensed water using the steam output by the molten salt heat storage and release device. The steam inlet of the third steam condenser is connected to the steam outlet of the first steam condenser, and the steam outlet of the third steam condenser is connected to the steam inlet of the condenser.

[0029] Optionally, a fifth steam condenser is provided between the third steam condenser and the steam of the condenser.

[0030] This technical solution uses superheated steam to heat cold molten salt to form hot molten salt and store it, uses steam passing through the molten salt heat storage and release device to supply heat and preheat condensate, and uses hot molten salt to heat part of the boiler feed water into low-temperature steam for power generation. The overall structure is simple, and it can achieve flexible peak regulation of thermal power units, ensure the operating efficiency of the units, and improve energy utilization.

[0031] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0033] Figure 1 This is a system block diagram of the peak-shaving system of a thermal power unit coupled with molten salt heat storage provided by the utility model;

[0034] Figure 2 It is a structural schematic diagram of a peak-shaving system of a thermal power unit coupled with molten salt heat storage provided by the utility model.

[0035] Description of Reference Numerals

[0036] 1-thermal power unit; 2-molten salt heat storage and release device; 3-preheating device;

[0037] 4-heat user; 11-superheater; 12-reheater;

[0038] 13- condenser; 14- condensate pump; 15- low-pressure heater group;

[0039] 16-deaerator; 17-feedwater pump; 18-high-pressure heater group;

[0040] 21-hot tank; 22-cold tank; 23-first steam condenser;

[0041] 24-second steam condenser; 25-feedwater heater; 26-hot salt drive pump;

[0042] 27-cold salt drive pump; 91-fourth steam condenser; 92-fifth steam condenser;

[0043] 101-high pressure cylinder; 102-medium pressure cylinder; 103-low pressure cylinder;

[0044] 901-first switch valve; 902-second switch valve; 903-third switch valve;

[0045] 904-first steam control valve; 905-second steam control valve. DETAILED DESCRIPTION

[0046] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not intended to limit the embodiment of the present invention.

[0047] In the embodiments of the present invention, unless otherwise specified, directional words such as "up, down, left, right" generally refer to the orientation or position relationship shown in the accompanying drawings, or the orientation or position relationship in which the utility model product is usually placed when in use.

[0048] The terms "first", "second", "third", etc. are only used for distinction and description and should not be understood as indicating or implying relative importance.

[0049] The terms "parallel" and "perpendicular" do not necessarily mean that the components must be absolutely parallel or perpendicular, but rather that they can be slightly tilted. For example, "parallel" simply means that the direction is more parallel than "perpendicular", not that the structure must be completely parallel, but rather that it can be slightly tilted.

[0050] Terms such as "horizontal," "vertical," and "overhanging" do not necessarily mean that a component must be absolutely horizontal, vertical, or overhanging. A slight tilt is permitted. For example, "horizontal" simply means that its direction is more horizontal than "vertical." It does not mean that the structure must be completely horizontal, but rather that a slight tilt is permitted.

[0051] Furthermore, terms like "approximately" and "substantially" are intended to clarify that the relevant content does not require absolute precision, but rather allows for certain deviations. For example, "approximately equal" does not simply mean absolute equality. Because absolute equality is difficult to achieve in actual production and operational processes, certain deviations generally exist. Therefore, in addition to absolute equality, "approximately equal" also encompasses the aforementioned situation of certain deviations. Taking this as an example, in other contexts, unless otherwise specified, terms like "approximately" and "substantially" have similar meanings as described above.

[0052] It should also be noted that, in the description of this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0053] Figure 1 This is a system block diagram of the peak-shaving system of a thermal power unit coupled with molten salt heat storage provided by the utility model; Figure 2 It is a structural schematic diagram of a peak-shaving system of a thermal power unit coupled with molten salt heat storage provided by the utility model.

[0054] like Figure 1-2 As shown, this embodiment provides a peak-shaving system for a thermal power unit coupled with molten salt heat storage, the system comprising:

[0055] Thermal power unit 1, used for heating feed water to generate superheated steam and heating low-temperature steam to generate reheated steam, and utilizing the superheated steam and reheated steam to generate electricity and generate condensate;

[0056] The molten salt heat storage and release device 2 is connected to the superheated steam outlet of the thermal power unit 1, and is used to use the superheated steam to heat the stored cold molten salt to form hot molten salt and store the hot molten salt, and use the hot molten salt to heat part of the feed water of the thermal power unit 1 into low-temperature steam and transport it to the thermal power unit 1;

[0057] The preheating device 3 is connected to the steam outlet of the molten salt heat storage and release device 2, and is used to heat the condensate with the steam output by the molten salt heat storage and release device 2. The heated condensate passes through the deaerator 16 of the thermal power unit 1 to form feed water;

[0058] The heat user 4 is connected to the steam outlet of the molten salt heat storage and release device 2, and is used to utilize the steam output by the molten salt heat storage and release device 2, and to transport the condensed water generated in the process of utilizing the steam to the thermal power unit 1;

[0059] The steam outlets of the preheating device 3 and the heat user 4 are connected to the steam inlet of the condenser 13 of the thermal power unit 1 .

[0060] Furthermore, the thermal power unit 1 includes:

[0061] Superheater 11, reheater 12, high-pressure cylinder 101, intermediate-pressure cylinder 102, low-pressure cylinder 103, and the condenser 13, condensate pump 14, low-pressure heater group 15, deaerator 16, feedwater pump 17 and high-pressure heater group 18 connected in sequence;

[0062] The water inlet of the superheater 11 is connected to the water outlet of the high-pressure heater group 18, and the steam outlet of the superheater 11 is connected to the steam inlet of the high-pressure cylinder 101;

[0063] The steam inlet of the reheater 12 is connected to the steam outlet of the high-pressure cylinder 101, the steam outlet of the reheater 12 is connected to the steam inlet of the intermediate-pressure cylinder 102, the steam outlet of the intermediate-pressure cylinder 102 is connected to the steam inlet of the low-pressure cylinder 103, and the steam outlet of the low-pressure cylinder 103 is connected to the steam inlet of the condenser 13.

[0064] The main shafts of the high-pressure cylinder 101, the intermediate-pressure cylinder 102, and the low-pressure cylinder 103 are connected to a generator for power generation. The low-pressure heater group 15 is composed of multiple stages of low-pressure heaters connected in series. The piping connection point between the low-pressure heater group 15 and the preheating device 3 (i.e., the first steam condenser) is located at the inlet or outlet of any low-pressure heater, allowing water to be drawn from a single or multiple points. The high-pressure heater group 18 is composed of multiple stages of high-pressure heaters connected in series. The piping connection point between the high-pressure heater group 18 and the feedwater heater 25 is located at the inlet or outlet of any high-pressure heater, allowing water to be drawn from a single or multiple points.

[0065] Furthermore, the molten salt heat storage and release device 2 includes:

[0066] Hot tank 21, used for storing hot molten salt;

[0067] a cold tank 22 for storing cold molten salt;

[0068] The first steam condenser 23 and the second steam condenser 24 are used to heat the molten salt using superheated steam. The steam inlets of the first steam condenser 23 and the second steam condenser 24 are both connected to the steam outlet of the superheater 11, the steam outlet of the first steam condenser 23 is connected to the steam inlet of the preheating device 3, and the steam outlet of the second steam condenser 24 is connected to the heat user 4. The cold molten salt inlets of the first steam condenser 23 and the second steam condenser 24 are both connected to the cold tank 22, and the hot molten salt outlets of the first steam condenser 23 and the second steam condenser 24 are both connected to the hot tank 21;

[0069] The feed water heater 25 is used to heat the feed water into low-temperature steam using hot molten salt. The hot molten salt inlet of the feed water heater 25 is connected to the hot tank 21, the cold molten salt outlet of the feed water heater 25 is connected to the cold tank 22, the feed water inlet of the feed water heater 25 is connected to the outlet of the feed water pump 17, and the steam outlet of the feed water heater 25 is connected to the steam inlet of the reheater 12.

[0070] Furthermore, a hot salt drive pump 26 is provided between the feed water heater 25 and the hot tank 21;

[0071] A cold salt driving pump 27 is provided between the first steam condenser 23 and the cold tank 22 , and between the second steam condenser 24 and the cold tank 22 .

[0072] Specifically, in this embodiment, the cold salt drive pump 27 disposed between the first steam condenser 23 and the cold tank 22 is named the first cold salt drive pump, and the cold salt drive pump 27 disposed between the second steam condenser 24 and the cold tank 22 is named the second cold salt drive pump. The hot salt drive pump 26 and the cold salt drive pump 27 are configured to adjust the flow rate of the molten salt, thereby achieving precise control of the flow rate.

[0073] Furthermore, the preheating device 3 includes:

[0074] The third steam condenser is used to heat the condensed water using the steam output by the molten salt heat storage and release device. The steam inlet of the third steam condenser is connected to the steam outlet of the first steam condenser 23, and the steam outlet of the third steam condenser is connected to the steam inlet of the condenser 13.

[0075] Specifically, in this embodiment, after the superheated steam is utilized by the molten salt heat storage and release device, it still has a certain temperature. Therefore, a third steam condenser is provided to reuse the remaining heat, and the heat absorbed by the third steam condenser is used to heat condensate, further improving energy utilization. Preferably, the condensate inlet of the third steam condenser is connected to the condensate outlet of the condenser 13, and the condensate outlet of the third steam condenser is connected to the outlet of the low-pressure heater group 15. After the steam is reused by the third steam condenser, the steam temperature needs to be further reduced so that condensate can be formed by the condenser 13. Therefore, a fifth steam condenser 92 is provided at the steam outlet of the third steam condenser.

[0076] In another embodiment, a first on-off valve 901 is provided between the feedwater heater 25 and the cold tank 22; a second on-off valve 902 is provided between the first steam condenser 23 and the hot tank 21; a third on-off valve 903 is provided between the second steam condenser 24 and the hot tank 21; a first steam control valve 904 is provided between the steam outlet of the superheater 11 and the first steam condenser 23; and a second steam control valve 905 is provided between the steam outlet of the superheater 11 and the second steam condenser 24. The above valves can be used to control the opening degree and the connection and disconnection of the pipeline.

[0077] The system provided by this solution optimizes the structure of the coupled heat storage system of the thermal power unit, realizes the decoupling of the boiler and the steam turbine, and uses the boiler steam supply system to extract the main steam used to drive the steam turbine to generate electricity when the power demand is low. The cold salt is heated through the heat exchanger, and the high-temperature molten salt is stored in the molten salt heat storage and release device. During the rapid load increase stage, the hot salt is used to heat the feed water through the molten salt heat storage and release device, and the low-temperature steam temperature is increased through the boiler reheater to produce high-temperature steam to make up for the energy loss of the main steam due to external heat supply. The molten salt heat storage and release device provides additional heat energy to the system when necessary to maintain the efficient operation of the system, realizing the efficient utilization and storage of heat energy, improving the heat utilization coefficient, reducing dependence on traditional energy, and has good practical value and promotion value.

[0078] In one specific implementation, the steam flow generated by the boiler is always set to the full-load steam flow rate. The steam turbine adjusts the steam flow rate accordingly as the grid load changes. Assuming the full-load output is 1000 (assuming this is a dimensionless relative flow rate value, the same applies below), the output required for direct main steam heating is 300.

[0079] During periods of low electricity demand, heat storage is necessary. When the turbine's operating load output is 700, 300 kilowatts of steam are extracted from the main steam supply. The steam is then reduced in temperature through the molten salt heat storage and release device, allowing the steam's heat to be provided to heat user 4. At this point, the second steam control valve 905 opens, the first and second on / off valves 901 and 902 close, the first cold salt drive pump shuts down, the second cold salt drive pump operates, the third on / off valve 903 opens, and the hot salt drive pump 26 shuts down. A portion of the main steam provided by the boiler superheater 11 enters the second steam condenser 24 via the steam pipeline. The low-temperature molten salt in the cold tank 22 enters the second steam condenser 24 via the molten salt pipeline, converting the main steam's thermal energy into that of the molten salt. The high-temperature molten salt enters the hot tank 21 through the molten salt pipeline. The steam, after heat exchange, enters the fourth steam condenser 91 for heat exchange, transferring its heat energy to the heat user 4. The water then returns to the condenser 13, where it is heated and then enters the deaerator 16.

[0080] When the turbine's operating load reaches 600, 400 kilowatts of steam are extracted from the main steam supply, 300 kilowatts of which are supplied to the user. The remaining 100 kilowatts of steam are directly used for heat storage. At this point, the first steam control valve 904 is open, the second steam control valve 905 is open, the first on-off valve 901 is closed, the second on-off valve 902 is open, the first cold salt pump and the second cold salt pump are operating, the third on-off valve 20 is open, and the hot salt pump 26 is shut down. The 300 kilowatts of main steam extracted from the boiler superheater 11 follows the same process as described above. Furthermore, the 100 kilowatts of main steam enters the first steam condenser 23 via the steam pipeline. The low-temperature molten salt in the cold tank 22 enters the first steam condenser 23 via the molten salt pipeline, where the main steam's thermal energy is converted into the molten salt's thermal energy. The high-temperature molten salt enters the hot tank 21 via the molten salt pipeline. The steam enters the preheating device 3 for heat exchange, then enters the fifth steam condenser 92 for heat exchange, where it transfers its thermal energy to condensate before returning to the condenser 13. This arrangement can facilitate the control of the flow direction of the low-temperature molten salt in the cold tank 22, thereby avoiding backflow and causing malfunctions.

[0081] During peak power demand, heat release is necessary. When the turbine's operating load is 800 kilowatts, the steam supplied to users is 300 kilowatts. At this point, the reheat steam operating load is 700 kilowatts, which is lower than the normal operating load of the turbine's low-pressure and medium-pressure cylinders. The reheat steam flow is insufficient, and the heat stored in the molten salt is used to heat the return water to generate an additional 100 kilowatts of reheat steam for replenishment. At this point, the first on-off valve 901 is opened, the first and second cold salt drive pumps are shut down, the second on-off valve 902 is closed, the third on-off valve 903 is closed, the hot salt drive pump 26 is operational, the first steam control valve 904 is closed, and the second steam control valve 905 is closed. A portion of the feedwater from the feedwater pump 17 enters the feedwater heater 25 through a pipeline for heat exchange. The high-temperature molten salt in the hot tank 21 enters the feedwater heater 25 through the molten salt pipeline, converting the thermal energy of the molten salt into thermal energy for the feedwater. The low-temperature molten salt enters the cold tank 22 through the molten salt pipeline. The heated feed water enters the boiler reheater 12, further raising the temperature to produce high-temperature hot reheat steam. This arrangement can easily control the flow of the high-temperature molten salt in the hot tank 21, avoiding backflow and causing malfunctions.

[0082] More specifically, the above control methods are all controlled by manual control.

[0083] In summary, during operation, the system first provides steam through the boiler's steam supply system, then sends superheated steam and reheated steam to the steam turbine, which drives the turbine to rotate the generator to generate electricity. At the same time, the molten salt heat storage and release device stores the power station's waste heat in molten salt. When power output needs to be rapidly increased, steam is generated through the molten salt heat storage and release, which is then fed into the steam turbine to meet power peak load requirements. This utility model is innovative and practical in its technical solution, has significant improvements, and is suitable for industrial promotion and application.

[0084] During the heat storage process, low-temperature molten salt can be heated by main steam, reheat steam, or electricity, either singly or in combination. After the steam exchanges heat with the molten salt, the exhaust steam can be used to replace the low-pressure heater extraction steam or directly enter the condenser. There are also multiple options for heat release. High-temperature molten salt can be used to produce main steam or reheat steam, and can also be used to heat single-stage or multi-stage high-pressure feed water.

[0085] This embodiment also provides a readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the above-mentioned control method for the peak-shaving system of a thermal power unit coupled with molten salt heat storage.

[0086] The above describes in detail the optional implementation methods of the embodiment of the present invention in conjunction with the accompanying drawings. However, the embodiment of the present invention is not limited to the specific details in the above implementation methods. Within the technical concept of the embodiment of the present invention, the technical solution of the embodiment of the present invention can be subjected to various simple modifications, and these simple modifications all fall within the protection scope of the embodiment of the present invention.

[0087] The above describes in detail the optional implementation methods of the present invention in conjunction with the accompanying drawings. However, the implementation methods of the present invention are not limited to the specific details in the above implementation methods. Within the technical concept of the implementation methods of the present invention, the technical solutions of the implementation methods of the present invention can be subjected to various simple modifications, and these simple modifications all fall within the scope of protection of the implementation methods of the present invention. It should also be noted that the various specific technical features described in the above specific implementation methods can be combined in any suitable manner unless there is any contradiction. In order to avoid unnecessary repetition, the various possible combinations of the implementation methods of the present invention will not be described separately.

[0088] In addition, the various implementations of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed in the embodiments of the present invention.

Claims

1. A peak-shaving system of a thermal power unit coupled with molten salt heat storage, characterized in that: The system comprises: Thermal power generation unit (1), used for heating feed water to generate superheated steam, heating low-temperature steam to form reheated steam, and using the superheated steam and reheated steam to generate electricity and form condensate; The molten salt heat storage and release device (2) is connected to the superheated steam outlet of the thermal power unit (1), and the hot steam enters the molten salt heat storage and release device (2) to heat the cold molten salt stored therein to form hot molten salt and store it. The formed hot molten salt can heat part of the feed water of the thermal power unit (1) into low-temperature steam and transport it to the thermal power unit (1); A preheating device (3) is connected to the steam outlet of the molten salt heat storage and release device (2) and is used to heat condensed water using the steam output by the molten salt heat storage and release device (2); the heated condensed water passes through the deaerator (16) of the thermal power unit (1) to form feed water; A heat user (4) is connected to the steam outlet of the molten salt heat storage and release device (2), and is used to utilize the steam output by the molten salt heat storage and release device (2), and to transport condensed water generated in the process of utilizing the steam to the thermal power unit (1); The steam outlets of the preheating device (3) and the heat user (4) are connected to the steam inlet of the condenser (13) of the thermal power unit (1).

2. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 1, characterized in that: The thermal power unit (1) comprises: A superheater (11), a reheater (12), a high-pressure cylinder (101), an intermediate-pressure cylinder (102), a low-pressure cylinder (103), and a condenser (13), a condensate pump (14), a low-pressure heater group (15), a deaerator (16), a feedwater pump (17), and a high-pressure heater group (18) connected in sequence; The water feed inlet of the superheater (11) is connected to the water feed outlet of the high-pressure heater group (18), and the steam outlet of the superheater (11) is connected to the steam inlet of the high-pressure cylinder (101); The steam inlet of the reheater (12) is connected to the steam outlet of the high-pressure cylinder (101), the steam outlet of the reheater (12) is connected to the steam inlet of the intermediate-pressure cylinder (102), the steam outlet of the intermediate-pressure cylinder (102) is connected to the steam inlet of the low-pressure cylinder (103), the steam outlet of the intermediate-pressure cylinder (102) is connected to the steam inlet of the low-pressure cylinder (103), and the steam outlet of the low-pressure cylinder (103) is connected to the steam inlet of the condenser (13).

3. The peak-shaving system of thermal power units coupled with molten salt heat storage according to claim 2, characterized in that: The low-pressure heater group (15) comprises a plurality of low-pressure heaters connected in series; The high-pressure heater group (18) includes a plurality of high-pressure heaters connected in series.

4. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 2, characterized in that: The molten salt heat storage and release device (2) comprises: A hot tank (21) for storing hot molten salt; a cold tank (22) for storing cold molten salt; A first steam condenser (23) and a second steam condenser (24) are used to heat molten salt using superheated steam, wherein the steam inlets of the first steam condenser (23) and the second steam condenser (24) are both connected to the steam outlet of the superheater (11), the steam outlet of the first steam condenser (23) is connected to the steam inlet of the preheating device (3), the steam outlet of the second steam condenser (24) is connected to the heat user (4), the cold molten salt inlets of the first steam condenser (23) and the second steam condenser (24) are both connected to the cold tank (22), and the hot molten salt outlets of the first steam condenser (23) and the second steam condenser (24) are both connected to the hot tank (21); The feedwater heater (25) is used to heat the feedwater into low-temperature steam using hot molten salt, wherein the hot molten salt inlet of the feedwater heater (25) is connected to the hot tank (21), the cold molten salt outlet of the feedwater heater (25) is connected to the cold tank (22), the feedwater inlet of the feedwater heater (25) is connected to the outlet of the feedwater pump (17), and the steam outlet of the feedwater heater (25) is connected to the steam inlet of the reheater (12).

5. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 4, characterized in that: A hot salt drive pump (26) is provided between the feed water heater (25) and the hot tank (21); A cold salt drive pump (27) is provided between the first steam condenser (23) and the cold tank (22), and between the second steam condenser (24) and the cold tank (22).

6. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 4, characterized in that: A first switch valve (901) is provided between the feed water heater (25) and the cold tank (22); a second switch valve (902) is provided between the first steam condenser (23) and the hot tank (21); and a third switch valve (903) is provided between the second steam condenser (24) and the hot tank (21).

7. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 4, characterized in that: A first steam control valve (904) is provided between the superheater (11) and the first steam condenser (23); and a second steam control valve (905) is provided between the superheater (11) and the second steam condenser (24).

8. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 4, characterized in that: A fourth steam condenser (91) is provided between the second steam condenser (24) and the heat user (4).

9. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 4, characterized in that: The preheating device (3) comprises: The third steam condenser is used to heat condensed water using the steam output by the molten salt heat storage and release device, the steam inlet of the third steam condenser is connected to the steam outlet of the first steam condenser (23), and the steam outlet of the third steam condenser is connected to the steam inlet of the condenser (13).

10. The peak-shaving system of a thermal power unit coupled with molten salt heat storage according to claim 9, characterized in that: A fifth steam condenser (92) is provided between the third steam condenser and the steam of the condenser (13).

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