A thermal power unit steam extraction thermal storage peak regulation system based on molten salt heat storage and its working method

Abstract

The present invention discloses a steam extraction thermal storage peak-shaving system for a thermal power unit based on molten salt heat storage and its operating method. The system comprises a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a condenser, a condensing pump, a low-pressure heating unit, a deaerator, a feedwater pump, a high-pressure heating unit, a molten salt cold tank, a low-temperature molten salt pump, a steam cooler, a molten salt hot tank, a high-temperature molten salt pump, a feedwater heater, a steam condenser, and a heat network water heater. The present invention can systematically utilize molten salt to store steam heat, achieving large-capacity, high-quality heat storage. Furthermore, the system can achieve zero output of the low-pressure cylinder, significantly reducing the power output of the thermal power unit, significantly improving the unit's flexibility, and achieving deep peak-shaving of the thermal power unit, with good economic benefits.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage technology, and in particular relates to a steam extraction thermal storage peak-shaving system for a thermal power unit based on molten salt heat storage and a working method. Background Art

[0002] As environmental protection goals continue to rise, higher demands are being placed on the flexibility of coal-fired power plants. To further enhance flexibility and adjustability and promote the clean, low-carbon transition of the power industry, coal-fired power plants need to be retrofitted and upgraded. These upgrades clearly define the peak-shaving capabilities of these plants. The general requirement for peak-shaving capacity in purely condensing operation is a minimum power output of 35% of rated load. During the heating season, heating-use thermal power plants should strive to achieve a minimum power output of 40% of rated load over a single six-hour period through thermoelectric decoupling. Other types of plants should take measures to minimize their minimum power output.

[0003] Coal-fired power units, due to their large base capacity, require large and high-quality energy storage for deep peak shaving. Existing electrochemical energy storage systems and hot water tank storage cannot meet these requirements. However, molten salt thermal storage, due to its large capacity and high thermal energy quality, is suitable for deep peak shaving. Molten salt thermal storage is a sensible heat storage method using molten inorganic salts. It uses changes in the molten salt temperature to store heat, typically using a dual-tank molten salt thermal storage system. Molten salt thermal storage is primarily used in solar thermal power plants, but is rarely used in large-scale coal-fired power units.

[0004] Under low-load conditions, coal-fired power units have low main steam (hot resteam) pressure and low steam condensation temperature. Of the heat contained in steam, sensible heat accounts for approximately 30% and latent heat accounts for 70%. Conventional thermal storage for peak load regulation uses hot water tanks or solid-state thermal storage, but these methods have limited storage capacity and low heat quality, making them suitable only for seasonal residential heating or heating low-pressure condensate, resulting in low economic returns. Molten salt thermal storage offers advantages such as large capacity and high thermal energy quality, but is limited by its high low-point operating temperature (140°C-260°C). Storing the latent heat of steam requires tens of thousands of tons of molten salt, necessitating significant engineering investment and hindering its application in deep peak load regulation for coal-fired power units. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a steam extraction thermal storage peak-shaving system and working method for thermal power units based on molten salt heat storage. The system uses molten salt to store the sensible heat of steam and uses condensate or hot network water to store the latent heat of steam. It can store heat in large capacity and high quality to achieve deep peak-shaving of the unit. The system molten salt flow rate is greatly reduced from 10,000 tons to 100 tons, which greatly reduces the project investment. At the same time, the stored latent heat heats the boiler feed water, reducing the high-quality steam extracted by the high-pressure heater, and has good economic benefits.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A steam extraction thermal storage peak-shaving system for a thermal power unit based on molten salt heat storage, comprising a boiler, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a condenser, a condensing pump, a low-pressure heating unit, a deaerator, a feedwater pump, a high-pressure heating unit, a molten salt cold tank, a low-temperature molten salt pump, a steam cooler, a molten salt hot tank, a high-temperature molten salt pump, a feedwater heater, a steam condenser, and a heat network water heater;

[0008] The steam outlet of the boiler is connected to the high-pressure cylinder inlet through a pipeline, the high-pressure cylinder outlet is connected to the boiler reheat steam inlet through a pipeline, the boiler reheat steam outlet is connected to the intermediate-pressure cylinder inlet through a pipeline, the intermediate-pressure cylinder, the low-pressure cylinder and the condenser are connected in sequence through pipelines, the condenser pump, the low-pressure heating unit, the deaerator, the feed water pump and the high-pressure heating unit are connected in sequence through pipelines, and the high-pressure heating unit outlet is connected to the boiler feed water inlet through a pipeline;

[0009] The molten salt cold tank, the low-temperature molten salt pump, the molten salt side of the steam cooler, the molten salt hot tank, the high-temperature molten salt pump and the molten salt side of the feedwater heater are connected in sequence through molten salt pipelines; the water side inlet and the water side outlet of the feedwater heater are connected to the high-pressure heating unit inlet and outlet respectively through pipelines;

[0010] The steam inlet of the steam cooler is connected to the boiler through a pipeline, and the steam outlet of the steam cooler is connected to the steam inlet of the steam condenser and the steam inlet of the heat network water heater through pipelines respectively; the condensate outlet of the steam condenser and the condensate outlet of the heat network water heater are connected to the deaerator after being combined through a pipeline; the condensate inlet and outlet of the steam condenser are connected to the inlet and outlet of the low-pressure heating unit respectively through pipelines;

[0011] The steam condenser condensate inlet, steam condenser condensate outlet, hot network water heater steam inlet, hot network water heater condensate outlet, the collecting pipe of hot network water heater condensate outlet and steam condenser condensate outlet, feed water heater water side inlet, feed water heater water side outlet, steam condenser condensate inlet and steam condenser condensate outlet are respectively equipped with No. 1 shut-off valve, No. 2 shut-off valve, No. 3 shut-off valve, No. 4 shut-off valve, No. 5 shut-off valve, No. 8 shut-off valve, No. 4 regulating valve, No. 7 shut-off valve and No. 3 regulating valve.

[0012] Preferably, the steam extraction thermal storage peak-shaving system of a thermal power unit based on molten salt heat storage of the present invention further includes a generator, and the main shafts of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are connected to the generator.

[0013] Preferably, the steam side inlet of the steam cooler is connected to the steam outlet of the boiler through a pipeline, and a first regulating valve is provided on the connecting pipeline.

[0014] Preferably, the steam side inlet of the steam cooler is connected to the hot resteam outlet of the boiler through a pipeline, and a second No. 1 regulating valve is provided on the connecting pipeline.

[0015] Preferably, a hot water inlet and outlet of the hot water heater are provided with a hot water inlet pipe and a return pipe, a No. 6 shut-off valve is arranged on the water inlet pipe, and a No. 2 regulating valve is arranged on the water outlet pipe.

[0016] Preferably, the low-pressure heating unit adopts the form of a single-stage low-pressure heater or multiple-stage low-pressure heaters connected in series, and the pipeline connection point between the low-pressure heating unit and the steam condenser is located at the inlet or outlet of any low-pressure heater.

[0017] Preferably, the high-pressure heating unit adopts a structure consisting of a single-stage high-pressure heater or multiple-stage high-pressure heaters connected in series, and the pipeline connection point between the high-pressure heating unit and the feedwater heater is located at the inlet or outlet of any high-pressure heater.

[0018] Preferably, the condensate pipeline of the steam condenser is led to the condenser or the interstage drain pipeline of the high-pressure heating unit or the interstage drain pipeline of the low-pressure heating unit.

[0019] Preferably, a coal-fired boiler, a gas-fired boiler, an oil-fired boiler, a biomass boiler, a waste heat boiler or an electrode boiler.

[0020] The working method of the thermal power unit extraction steam thermal storage peak-shaving system based on molten salt heat storage of the present invention includes the following steps:

[0021] Energy storage operating condition: The boiler provides high-temperature steam to the steam side of the steam cooler, starts the low-temperature molten salt pump, opens the No. 5 shut-off valve, No. 7 shut-off valve and No. 3 regulating valve, stops the high-temperature molten salt pump, closes the No. 8 shut-off valve and No. 4 regulating valve. At this time, the steam discharged from the boiler heats the molten salt after heat exchange through the steam cooler. The heated molten salt is stored in the molten salt hot tank, and the condensate of the low-pressure heating unit is bypassed by the condensate side of the steam condenser; when the latent heat of steam heats the condensate, the No. 3 shut-off valve and No. 4 shut-off valve are closed, and the No. 1 shut-off valve and No. 2 shut-off valve are opened; when the latent heat of steam heats the hot network water, the No. 1 shut-off valve and No. 2 shut-off valve are closed, and the No. 3 shut-off valve and No. 4 shut-off valve are opened; under the energy storage operating condition, the sensible heat of steam is converted into the sensible heat of molten salt and stored in the molten salt hot tank, and the latent heat of steam is converted into the sensible heat of condensate or the sensible heat of hot network water;

[0022] Energy release condition: Stop the low-temperature molten salt pump, close the No. 1 regulating valve, No. 1 shut-off valve, No. 2 shut-off valve, No. 3 shut-off valve, No. 4 shut-off valve, No. 5 shut-off valve, No. 7 shut-off valve and No. 3 regulating valve, start the high-temperature molten salt pump, open the No. 8 shut-off valve and No. 4 regulating valve; the opening of the No. 4 regulating valve controls the bypass water volume of the high-pressure heating unit, thereby controlling the outlet water temperature of the feedwater heater;

[0023] Other operating conditions: Shut down the high-temperature molten salt pump and the low-temperature molten salt pump, and close the No. 1 regulating valve, No. 1 shut-off valve, No. 2 shut-off valve, No. 3 shut-off valve, No. 4 shut-off valve, No. 5 shut-off valve, No. 8 shut-off valve, No. 4 regulating valve, No. 7 shut-off valve, and No. 3 regulating valve.

[0024] The present invention has the following beneficial effects:

[0025] The present invention's thermal power unit extraction steam storage peak-shaving system based on molten salt heat storage utilizes molten salt heat storage to achieve deep peak-shaving of the thermal power unit, improves the flexibility of the thermal power unit, stores the sensible heat of steam in molten salt through a steam cooler, and stores the latent heat of steam in condensate or hot network water through a steam condenser or a hot network water heater, which can greatly reduce the amount of molten salt in the heat storage process; the heat stored in the molten salt is used to heat the boiler feed water through the feed water heater, which can reduce the steam extraction amount of the high-pressure heater, increase steam work, and reduce the heat consumption of the unit. In summary, the thermal power unit extraction steam storage peak-shaving system based on molten salt heat storage of the present invention utilizes molten salt to store the sensible heat of steam and utilizes condensate or hot network water to store the latent heat of steam, which can store heat in large capacity and high quality, achieve deep peak-shaving of the unit, and significantly reduce the system's molten salt flow rate from 10,000 tons to 100 tons, significantly reducing project investment. At the same time, the stored latent heat heats the boiler feed water, reducing the high-quality steam extracted by the high-pressure heater, and has good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural schematic diagram of the steam extraction thermal storage peak-shaving system of a thermal power unit based on molten salt heat storage according to the present invention.

[0027] In the figure, 1 is a boiler, 2 is a high-pressure cylinder, 3 is a medium-pressure cylinder, 4 is a low-pressure cylinder, 5 is a condenser, 6 is a condensate pump, 7 is a low-pressure heating unit, 8 is a deaerator, 9 is a feed water pump, 10 is a high-pressure heating unit, 11 is a generator, 12 is a molten salt cold tank, 13 is a low-temperature molten salt pump, 14 is a steam condensing device, 15 is a molten salt hot tank, 16 is a high-temperature molten salt pump, 17 is a feed water heater, 18 is a steam condenser, 19 is a heat network water heater, 20 is the first regulating valve, 20-1 is the second regulating valve, 21 is the No. 1 shut-off valve, 22 is the No. 2 shut-off valve, 23 is the No. 3 shut-off valve, 24 is the No. 4 shut-off valve, 25 is the No. 5 shut-off valve, 26 is the No. 6 shut-off valve, 27 is the No. 2 regulating valve, 28 is the No. 8 shut-off valve, 29 is the No. 4 regulating valve, 30 is the No. 7 shut-off valve, and 31 is the No. 3 regulating valve. DETAILED DESCRIPTION

[0028] The present invention is described in further detail below with reference to the accompanying drawings:

[0029] like Figure 1As shown, the steam extraction thermal storage peak-shaving system of a thermal power unit based on molten salt heat storage of the present invention includes a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a condenser 5, a condensate pump 6, a low-pressure heating unit 7, a deaerator 8, a feedwater pump 9, a high-pressure heating unit 10, and a generator 11; it also includes a molten salt cold tank 12, a low-temperature molten salt pump 13, a steam cooler 14, a molten salt hot tank 15, a high-temperature molten salt pump 16, a feedwater heater 17, a steam condenser 18, and a heat network water heater 19;

[0030] The steam outlet of boiler 1 is connected to the inlet of high-pressure cylinder 2 through a pipeline, the outlet of high-pressure cylinder 2 is connected to the reheat steam inlet of boiler 1 through a pipeline, the reheat steam outlet of boiler 1 is connected to the inlet of intermediate-pressure cylinder 3 through a pipeline, the intermediate-pressure cylinder 3, the low-pressure cylinder 4 and the condenser 5 are connected in sequence through pipelines, the outlet of condenser 5, the inlet of condensate pump 6, the inlet of low-pressure heating unit 7, the inlet of deaerator 8, the inlet of feedwater pump 9 and the inlet of high-pressure heating unit 10 are connected in sequence through pipelines, and the outlet of high-pressure heating unit 10 is connected to the feedwater inlet of boiler 1 through a pipeline; the main shafts of high-pressure cylinder 2, intermediate-pressure cylinder 3 and low-pressure cylinder 4 are connected to generator 11;

[0031] The outlet of the molten salt cold tank 12 is connected to the inlet of the low-temperature molten salt pump 13, the outlet of the low-temperature molten salt pump 13 is connected to the molten salt side inlet (i.e., the cold inlet) of the steam cooler 14, the molten salt side outlet (i.e., the cold outlet) of the steam cooler 14 is connected to the inlet of the molten salt hot tank 15, the inlet of the high-temperature molten salt pump 16 is connected to the molten salt hot tank 15, the outlet of the high-temperature molten salt pump 16 is connected to the molten salt side inlet of the feedwater heater 17, and the molten salt side outlet of the feedwater heater 17 is connected to the inlet of the molten salt cold tank 12, forming a closed cycle;

[0032] The steam side inlet of the steam cooler 14 is connected to the steam outlet of the boiler 1 through a pipeline, and a first regulating valve 20 is arranged on the pipeline. The steam side outlet of the steam cooler 14 is divided into two paths through the pipeline. The two paths are connected to the steam inlet of the steam condenser 18 and the steam inlet of the hot network water heater 19 respectively. A No. 1 shut-off valve 21 and a No. 3 shut-off valve 23 are arranged on the two pipelines of the steam inlet of the steam condenser 18 and the hot network water heater 19 respectively; the condensate outlet of the steam condenser 18 and the condensate outlet of the hot network water heater 19 are connected to the inlet of the deaerator 8 after being combined through a pipeline. The condensate outlet of the steam condenser 18 and the hot network water heater 19 are connected to the inlet of the deaerator 8. A No. 2 shut-off valve 22 and a No. 4 shut-off valve 24 are respectively arranged on the water heater 19, and a No. 5 shut-off valve 25 is arranged on the collecting pipe; the hot network water inlet and outlet of the hot network water heater 19 are provided with a hot network inlet and return pipeline, a No. 6 shut-off valve 26 is arranged on the inlet pipe of the hot network inlet and return pipeline, and a No. 2 regulating valve 27 is arranged on the outlet pipe of the hot network inlet and return pipeline; the condensate inlet of the steam condenser 18 is connected to the inlet of the low-pressure heating unit 7 through a pipeline, and a No. 7 shut-off valve 30 is arranged on the pipeline, and the condensate outlet of the steam condenser 18 is connected to the outlet of the low-pressure heating unit 7 through a pipeline, and a No. 3 regulating valve 31 is arranged on the pipeline. The water inlet of the feedwater heater 17 is connected to the inlet of the high-pressure heating unit 10 via a pipeline, which is equipped with a No. 8 shutoff valve 28. The water outlet of the feedwater heater 17 is connected to the outlet of the high-pressure heating unit 10 via a pipeline, which is equipped with a No. 4 regulating valve 29. In the above system, the steam cooler 14's steam extraction point is located at the steam outlet of boiler 1 or the hot reheat outlet of boiler 1. The steam extraction pipeline of the latter is equipped with a No. 2 No. 1 regulating valve 20-1. The sensible heat of the steam is stored in molten salt by the steam cooler 14, while the latent heat of the steam is stored in condensate by the steam condenser 18 or heated by the hot water network heater 19. The condensate from the steam condenser 18 is routed to the deaerator 8, condenser 5, or the interstage drain pipe of the high-pressure heating unit 10 or the interstage drain pipe of the low-pressure heating unit 7. Boiler 1 is a steam-generating device, such as a coal-fired boiler, a gas-fired boiler, an oil-fired boiler, a biomass boiler, a waste heat boiler, or an electrode boiler. The low-pressure heating unit 7 adopts the form of a one-stage low-pressure heater or a multi-stage low-pressure heater in series. The pipeline connection point between the low-pressure heating unit 7 and the steam condenser 18 is located at the inlet or outlet of any low-pressure heater, and water is taken at a single point or multiple points to achieve adjustable water intake temperature and flow; the high-pressure heating unit 10 adopts the form of a one-stage high-pressure heater or a multi-stage high-pressure heater in series. The pipeline connection point between the high-pressure heating unit 10 and the water feed heater 17 is located at the inlet or outlet of any high-pressure heater, and water is taken at a single point or multiple points to achieve adjustable water intake temperature and flow.

[0033] like Figure 1 As shown, the working method of the steam extraction thermal storage peak-shaving system of a thermal power unit based on molten salt heat storage of the present invention includes the following process:

[0034] Energy storage working condition: start the low-temperature molten salt pump 13, open the No. 1 regulating valve 20, No. 5 shut-off valve 25, No. 7 shut-off valve 30 and No. 3 regulating valve 31, stop the high-temperature molten salt pump 16, close the No. 8 shut-off valve 28 and No. 4 regulating valve 29; if the steam latent heat heats the condensate, it is also necessary to close the No. 3 shut-off valve 23, No. 4 shut-off valve 24, No. 6 shut-off valve 26 and No. 2 regulating valve 27, open the No. 1 shut-off valve 21 and No. 2 shut-off valve 22; if the steam latent heat heats the hot network water, it is also necessary to close the No. 1 shut-off valve 21 and No. 2 shut-off valve 22, open the No. 3 shut-off valve 23, No. 4 shut-off valve 24, No. 6 shut-off valve 26 and No. 2 regulating valve 2 7; If the latent heat of steam heats the condensate, when all the condensate of the low-pressure heating unit 7 is bypassed, the amount of extracted steam reaches the maximum, and the maximum peak-shaving capacity of the system is reached at this time; If the latent heat of steam heats the hot network water, the peak-shaving capacity of the unit increases with the increase of the amount of hot network water; Under the energy storage condition, the sensible heat of steam is converted into molten salt sensible heat and stored in the molten salt heat tank 15, and the latent heat of steam is converted into sensible heat of condensate or sensible heat of hot network water. Under the condition that the evaporation amount of the boiler remains unchanged, the steam work is reduced to achieve the peak-shaving of the unit; When the extracted steam source is boiler hot re-steam, the first No. 1 regulating valve 20 corresponds to the second No. 1 regulating valve 20-1, and the rest of the working methods remain unchanged;

[0035] Energy release condition: Shut down the low-temperature molten salt pump 13, close the No. 1 regulating valve 20, No. 1 shut-off valve 21, No. 2 shut-off valve 22, No. 3 shut-off valve 23, No. 4 shut-off valve 24, No. 5 shut-off valve 25, No. 6 shut-off valve 26, No. 2 regulating valve 27, No. 7 shut-off valve 30, and No. 3 regulating valve 31, start the high-temperature molten salt pump 16, and open the No. 8 shut-off valve 28 and No. 4 regulating valve 29; the opening of the No. 4 regulating valve 29 controls the bypass water volume of the high-pressure heating unit 10, thereby controlling the outlet water temperature of the feedwater heater 17. When all the feedwater of the high-pressure heating unit 10 is bypassed, the energy release rate reaches its maximum; under the energy release condition, the sensible heat of the molten salt is converted into the sensible heat of the feedwater. Under the condition that the evaporation rate of the boiler remains unchanged, the steam extraction of the turbine is reduced, the steam work is increased, and the power generation capacity of the unit is improved;

[0036] Other operating conditions: Shut down the high-temperature molten salt pump 16 and the low-temperature molten salt pump 13, close the No. 1 regulating valve 20, No. 1 shut-off valve 21, No. 2 shut-off valve 22, No. 3 shut-off valve 23, No. 4 shut-off valve 24, No. 5 shut-off valve 25, No. 6 shut-off valve 26, No. 2 regulating valve 27, No. 8 shut-off valve 28, No. 4 regulating valve 29, No. 7 shut-off valve 30 and No. 3 regulating valve 31, isolate the peak-shaving system from the unit, and operate the unit normally.

[0037] From the above, it can be seen that the present invention can systematically utilize molten salt to store steam heat, realizing large-capacity, high-quality heat storage. At the same time, the system of the present invention can achieve zero output of the low-pressure cylinder, deeply reduce the power output of the thermal power unit, greatly improve the flexibility of the unit, realize deep peak regulation of the thermal power unit, and have good economic benefits.

Claims

1. A steam extraction thermal storage peak regulation system for thermal power units based on molten salt heat storage, characterized in that: It includes a boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a condenser (5), a condensate pump (6), a low-pressure heating unit (7), a deaerator (8), a feed water pump (9), a high-pressure heating unit (10), a molten salt cold tank (12), a low-temperature molten salt pump (13), a steam cooler (14), a molten salt hot tank (15), a high-temperature molten salt pump (16), a feed water heater (17), a steam condenser (18) and a hot water network heater (19); The steam outlet of the boiler (1) is connected to the inlet of the high-pressure cylinder (2) through a pipeline, the outlet of the high-pressure cylinder (2) is connected to the reheat steam inlet of the boiler (1) through a pipeline, the reheat steam outlet of the boiler (1) is connected to the inlet of the medium-pressure cylinder (3) through a pipeline, the medium-pressure cylinder (3), the low-pressure cylinder (4) and the condenser (5) are connected in sequence through pipelines, the condenser pump (6) of the condenser (5), the low-pressure heating unit (7), the deaerator (8), the feed water pump (9) and the high-pressure heating unit (10) are connected in sequence through pipelines, and the outlet of the high-pressure heating unit (10) is connected to the feed water inlet of the boiler (1) through a pipeline; The molten salt cold tank (12), the low-temperature molten salt pump (13), the molten salt side of the steam cooler (14), the molten salt hot tank (15), the high-temperature molten salt pump (16), and the molten salt side of the feed water heater (17) are sequentially connected through molten salt pipelines; the water side inlet and the water side outlet of the feed water heater (17) are respectively connected to the inlet and outlet of the high-pressure heating unit (10) through pipelines; The steam side inlet of the steam cooler (14) is connected to the boiler (1) through a pipeline, and the steam side outlet of the steam cooler (14) is respectively connected to the steam inlet of the steam condenser (18) and the steam inlet of the hot water network heater (19) through pipelines; the condensate outlet of the steam condenser (18) and the condensate outlet of the hot water network heater (19) are connected to the deaerator (8) after being combined through a pipeline; the condensate inlet and outlet of the steam condenser (18) are respectively connected to the inlet and outlet of the low-pressure heating unit (7) through pipelines; A No. 1 shutoff valve (21), a No. 2 shutoff valve (22), a No. 3 shutoff valve (23), a No. 4 shutoff valve (24), a No. 5 shutoff valve (25), a No. 8 shutoff valve (28), a No. 4 regulating valve (29), a No. 7 shutoff valve (30) and a No. 3 regulating valve (31) are respectively provided on the condensate inlet of the steam condenser (18), the condensate outlet of the steam condenser (18), the steam inlet of the hot water heater (19), the condensate outlet of the hot water heater (19), the collecting pipe of the condensate outlet of the hot water heater (19) and the condensate outlet of the steam condenser (18); The steam extraction thermal storage peak regulation system for thermal power generation units based on molten salt heat storage further comprises a generator (11), and the main shafts of the high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) are connected to the generator (11); The steam side inlet of the steam cooler (14) is connected to the steam outlet of the boiler (1) through a pipeline, and a first regulating valve (20) is provided on the connecting pipeline.

2. The extraction steam thermal storage peak-shaving system for thermal power units based on molten salt heat storage according to claim 1 is characterized in that: The hot water inlet and outlet of the hot water heater (19) are provided with a hot water inlet pipe and a return pipe. A No. 6 shut-off valve (26) is arranged on the inlet pipe, and a No. 2 regulating valve (27) is arranged on the outlet pipe.

3. The extraction steam thermal storage peak-shaving system for thermal power units based on molten salt heat storage according to claim 1, characterized in that: The low-pressure heating unit (7) adopts the form of a single-stage low-pressure heater or a multi-stage low-pressure heater connected in series, and the pipeline connection point between the low-pressure heating unit (7) and the steam condenser (18) is located at the inlet or outlet of any low-pressure heater.

4. The extraction steam thermal storage peak-shaving system for thermal power units based on molten salt heat storage according to claim 3 is characterized in that: The high-pressure heating unit (10) adopts a structure consisting of a single-stage high-pressure heater or multiple-stage high-pressure heaters connected in series, and the pipe connection point between the high-pressure heating unit (10) and the feedwater heater (17) is located at the inlet or outlet of any high-pressure heater.

5. The extraction steam thermal storage peak-shaving system for thermal power units based on molten salt heat storage according to claim 4 is characterized in that: The condensate pipeline of the steam condenser (18) is led to the interstage drain pipeline of the condenser or the high-pressure heating unit (10) or the interstage drain pipeline of the low-pressure heating unit (7).

6. The extraction steam thermal storage peak-shaving system for thermal power units based on molten salt heat storage according to claim 1, characterized in that: Coal-fired boiler, gas-fired boiler, oil-fired boiler, biomass boiler, waste heat boiler or electrode boiler.

7. The operating method of the molten salt heat storage-based extraction steam thermal storage peak-shaving system for thermal power generation units according to any one of claims 1 to 6, characterized in that: The process includes the following: Energy storage working condition: The boiler (1) provides high-temperature steam to the steam side of the steam cooler (14), starts the low-temperature molten salt pump (13), opens the No. 5 shut-off valve (25), the No. 7 shut-off valve (30) and the No. 3 regulating valve (31), stops the high-temperature molten salt pump (16), closes the No. 8 shut-off valve (28) and the No. 4 regulating valve (29), at this time, the steam discharged from the boiler (1) heats the molten salt after heat exchange through the steam cooler (14), and the heated molten salt is stored in the molten salt hot tank (15), and the condensate of the low-pressure heating unit (7) is condensed by the steam. The condensate side bypass of the device (18); when the steam latent heat heats the condensate, the No. 3 shut-off valve (23) and the No. 4 shut-off valve (24) are closed, and the No. 1 shut-off valve (21) and the No. 2 shut-off valve (22) are opened; when the steam latent heat heats the hot network water, the No. 1 shut-off valve (21) and the No. 2 shut-off valve (22) are closed, and the No. 3 shut-off valve (23) and the No. 4 shut-off valve (24) are opened; under the energy storage condition, the steam sensible heat is converted into the molten salt sensible heat and stored in the molten salt hot tank (15), and the steam latent heat is converted into the condensate sensible heat or the hot network water sensible heat; Energy release working condition: stop the low-temperature molten salt pump (13), close the No. 1 regulating valve (20), No. 1 shut-off valve (21), No. 2 shut-off valve (22), No. 3 shut-off valve (23), No. 4 shut-off valve (24), No. 5 shut-off valve (25), No. 7 shut-off valve (30) and No. 3 regulating valve (31), start the high-temperature molten salt pump (16), open the No. 8 shut-off valve (28) and No. 4 regulating valve (29); the opening of the No. 4 regulating valve (29) controls the bypass water volume of the high-pressure heating unit (10), thereby controlling the outlet water temperature of the feedwater heater (17); Other working conditions: shut down the high-temperature molten salt pump (16) and the low-temperature molten salt pump (13), close the No. 1 regulating valve (20), No. 1 shut-off valve (21), No. 2 shut-off valve (22), No. 3 shut-off valve (23), No. 4 shut-off valve (24), No. 5 shut-off valve (25), No. 8 shut-off valve (28), No. 4 regulating valve (29), No. 7 shut-off valve (30), and No. 3 regulating valve (31).

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