Steam sensible heat cascade storage combined heat and power generation peak regulation system and working method

Abstract

The invention discloses a combined heat and power generation peak regulation system with steam sensible heat cascade storage and a working method. Steam supplies heat to a high-temperature heat user, a medium-temperature heat user and a low-temperature heat user from a steam turbine high-pressure cylinder and a steam turbine medium-low-pressure cylinder; before the steam is conveyed to a heat user, part of sensible heat of the steam is stored into a molten salt energy storage system through a high-temperature sensible heat exchanger, a medium-temperature sensible heat exchanger and a low-temperature sensible heat exchanger, and the steam sensible heat is conveyed to the heat user after being stored and cooled to reach the heat supply temperature; when the molten salt is used for heating the supplied water, the supplied water is heated into low-temperature heat supply steam, medium-temperature heat supply steam and high-temperature heat supply steam through a low-temperature heater, a medium-temperature heater and a high-temperature heater in sequence to be conveyed to heat consumers; the molten salt energy storage system is configured to store sensible heat of multiple streams of steam in molten salt to reduce the temperature, meanwhile, the molten salt is heated in an echelon mode, heat is completely supplied through the molten salt energy storage system by releasing the molten salt during peak regulation of the combined heat and power generation unit, and then the purpose of complete thermoelectric decoupling is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of improving the peak-shaving capability of a coal-fired cogeneration unit, and in particular to a cogeneration peak-shaving system with cascaded storage of steam sensible heat and a working method. Background Art

[0002] At present, with the large-scale grid connection of new energy, the proportion of new energy power generation is increasing. However, due to the large fluctuation of energy supply over time, it is currently impossible to effectively predict the daily production capacity of new energy, which will destroy the supply and demand balance on the power grid side and affect the power supply of the power grid. Coal-fired units have certain flexibility in participating in peak load regulation and frequency regulation. Therefore, improving the peak load regulation capacity of coal-fired cogeneration units is an effective solution. At present, there are mainly peak load regulation methods such as coupled energy storage systems and low-pressure cylinder zero output. However, the coupled energy storage system stores steam heat, which has a large heat exchange temperature difference and a large amount of system available energy loss, resulting in low operating efficiency of the energy storage system and affecting the economic efficiency of operation. At the same time, the temperature regulation of traditional heating steam is achieved through cooling water, and the available energy loss of heating steam is large. For multiple heat users, there is a low energy utilization rate. Summary of the invention

[0003] In order to solve the above problems, the purpose of the present invention is to propose a cogeneration peak-shaving system and working method with cascade storage of steam sensible heat. The present invention configures a molten salt energy storage system to store multiple streams of steam sensible heat in molten salt to reduce the temperature, avoiding the control of the heating temperature by cooling water. At the same time, the molten salt is heated in stages to reduce the heat exchange temperature difference. When the cogeneration unit is peak-shaving, the molten salt is released and the molten salt energy storage system is used to completely supply heat, thereby achieving the purpose of complete decoupling of heat and electricity.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is:

[0005] A combined heat and power peak-shaving system with steam sensible heat cascade storage, comprising a combined heat and power unit and a molten salt energy storage system;

[0006] The cogeneration unit comprises a boiler 1, a steam turbine high-pressure cylinder 2, a steam turbine medium- and low-pressure cylinders 3, a condenser 4, a condensate pump 5, a deaerator 6, a feed water pump 7, a high-pressure regenerator 8, a high-temperature heating valve 9, a medium-temperature heating valve 10, a low-temperature heating valve 11 and a heating feed water valve 12; the main steam outlet of the boiler 1 is connected to the inlet of the steam turbine high-pressure cylinder 2, the outlet of the steam turbine high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1, the reheat steam outlet of the boiler 1 is connected to the inlet of the steam turbine medium- and low-pressure cylinders 3, the outlet of the steam turbine medium- and low-pressure cylinders 3 is connected to the inlet of the condenser 4, the outlet of the condenser 4 is connected to the inlet of the condensate pump 5, the outlet of the condensate pump 5 is connected to the inlet of the deaerator 6, the outlet of the deaerator 6 is connected to the feed water inlet of the high-pressure regenerator 8, and the feed water outlet of the high-pressure regenerator 8 is connected to the feed water inlet of the boiler 1;

[0007] The molten salt energy storage system comprises a cold salt tank 13, a hot salt tank 14, a cold salt pump 15, a cold salt valve 16, a low-temperature sensible heat exchanger 17, a medium-temperature sensible heat exchanger 18, a high-temperature sensible heat exchanger 19, a hot salt pump 20, a hot salt valve 21, a low-temperature heater 22, a medium-temperature heater 23, a high-temperature heater 24, a low-temperature heating valve 25 of the energy storage system, a medium-temperature heating valve 26 of the energy storage system, and a high-temperature heating valve 27 of the energy storage system; the outlet of the cold salt tank 13 is connected to the inlet of the cold salt pump 15, the outlet of the cold salt pump 15 is connected to the inlet of the cold salt valve 16, the outlet of the cold salt valve 16 is connected to the inlet of the molten salt side of the low-temperature sensible heat exchanger 17, the outlet of the low-temperature sensible heat exchanger 17 is connected to the molten salt side of the medium-temperature sensible heat exchanger 18, and the outlet of the low-temperature sensible heat exchanger 17 is connected to the molten salt side of the medium-temperature sensible heat exchanger 18. The heat exchanger 18 is connected to the molten salt side inlet, the medium-temperature sensible heat exchanger 18 molten salt side outlet is connected to the high-temperature sensible heat exchanger 19 molten salt side inlet, and the high-temperature sensible heat exchanger 19 molten salt side outlet is connected to the hot salt tank 14 inlet; the hot salt tank 14 outlet is connected to the hot salt pump 20 inlet, the hot salt pump 20 outlet is connected to the hot salt valve 21 inlet, the hot salt valve 21 outlet is connected to the molten salt side inlet of the low-temperature heater 22, the molten salt side outlet of the low-temperature heater 22 is connected to the molten salt side inlet of the medium-temperature heater 23, the molten salt side outlet of the medium-temperature heater 23 is connected to the molten salt side inlet of the high-temperature heater 24, and the molten salt side outlet of the high-temperature heater 24 is connected to the cold salt tank 13 inlet;

[0008] The coupling connection relationship between the cogeneration unit and the molten salt energy storage system is as follows:

[0009] The main steam outlet of boiler 1 is connected to the steam side inlet of high temperature sensible heat exchanger 19 through high temperature heating valve 9; the outlet of high pressure cylinder 2 is connected to the steam side inlet of medium temperature sensible heat exchanger 18 through medium temperature heating valve 10; the steam extraction port of medium and low pressure cylinder 3 is connected to the steam side inlet of low temperature sensible heat exchanger 17 through low temperature heating valve 11; the steam sides of low temperature sensible heat exchanger 17, medium temperature sensible heat exchanger 18 and high temperature sensible heat exchanger 19 are connected to low temperature heat users, medium temperature heat users and high temperature heat users respectively;

[0010] The outlet of the feed water pump 7 is connected to the steam side inlet of the low-temperature heater 22 of the molten salt energy storage system through the heating water supply valve 12. The steam side outlet of the low-temperature heater 22 is connected to the steam side inlet of the medium-temperature heater 23 and the inlet of the low-temperature heating valve 25 of the energy storage system. The steam side outlet of the medium-temperature heater 23 is connected to the steam side inlet of the high-temperature heater 24 and the inlet of the medium-temperature heating valve 26 of the energy storage system. The steam side outlet of the high-temperature heater 24 is connected to the inlet of the high-temperature heating valve 27 of the energy storage system.

[0011] The working method of the cogeneration peak-shaving system with a steam sensible heat cascade storage is as follows: steam is supplied from the high-pressure cylinder 2 of the steam turbine and the medium- and low-pressure cylinders 3 of the steam turbine to high-temperature heat users, medium-temperature heat users, and low-temperature heat users; before being supplied to the heat users, part of the sensible heat of the steam is stored in the molten salt energy storage system through the high-temperature sensible heat exchanger 19, the medium-temperature sensible heat exchanger 18, and the low-temperature sensible heat exchanger 17, respectively, and after the sensible heat of the steam is stored, it is cooled to the heating temperature and then supplied to the heat users respectively; and when the molten salt is used to heat the water supply, the water supply is heated into low-temperature heating steam, medium-temperature heating steam, and high-temperature heating steam through the low-temperature heater 22, the medium-temperature heater 23, and the high-temperature heater 24 in turn, and is supplied to the heat users;

[0012] When the cogeneration unit is at waist load, the cogeneration unit stores heat; the high-temperature heating valve 9, the medium-temperature heating valve 10, and the low-temperature heating valve 11 are opened; the low-temperature heating steam, the medium-temperature heating steam, and the high-temperature heating steam respectively pass through the low-temperature sensible heat exchanger 17, the medium-temperature sensible heat exchanger 18, and the high-temperature sensible heat exchanger 19 to store a part of the sensible heat in the molten salt, thereby avoiding the loss of available energy due to the mixed cooling water; and the low-temperature salt is heated in stages through the low-temperature sensible heat exchanger 17, the medium-temperature sensible heat exchanger 18, and the high-temperature sensible heat exchanger 19 in turn, thereby reducing the heat exchange temperature difference;

[0013] When the cogeneration unit is in the peak regulation process, it is necessary to completely use the molten salt energy storage system for heat supply, so as to realize heat and electricity decoupling; at this time, close the high-temperature heating valve 9, the medium-temperature heating valve 10, and the low-temperature heating valve 11; open the heating water supply valve 12, and extract the deoxygenated and pressurized supercooled water from the deaerator 6 through the water supply pump 7, and heat it into low-temperature heating steam, medium-temperature heating steam, and high-temperature heating steam in turn through the low-temperature heater 22, the medium-temperature heater 23, and the high-temperature heater 24 to replace the steam extraction from the turbine to heat the heat users; the low-temperature steam is pressure-regulated by the low-temperature heating valve 25 of the energy storage system, the medium-temperature steam is pressure-regulated by the medium-temperature heating valve 26 of the energy storage system, and the high-temperature steam is pressure-regulated by the high-temperature heating valve 27 of the energy storage system, and the heat load is completely provided by the heat storage system.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] (1) The present invention designs a molten salt energy storage system to store the sensible heat of multiple steam streams in molten salt to reduce the temperature, thereby avoiding the need to control the heating temperature through cooling water and reducing the available energy loss of the heating steam;

[0016] (2) In the present invention, during the molten salt heating and heat release process, step-by-step heat exchange is achieved according to the temperatures of the cold and hot fluids, thereby reducing the heat exchange temperature difference, achieving the purpose of step-by-step energy utilization, and increasing the economic efficiency of the molten salt energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the combined heat and power peak-shaving system with cascaded storage of steam sensible heat according to the present invention.

[0018] In the figure: 1 is a boiler, 2 is a high-pressure cylinder of a steam turbine, 3 is a medium- and low-pressure cylinder of a steam turbine, 4 is a condenser, 5 is a condensate pump, 6 is a deaerator, 7 is a feed water pump, 8 is a high-pressure regenerator, 9 is a high-temperature heating valve, 10 is a medium-temperature heating valve, 11 is a low-temperature heating valve, 12 is a heating feed water valve, 13 is a cold salt tank, 14 is a hot salt tank, 15 is a cold salt pump, 16 is a cold salt valve, 17 is a low-temperature sensible heat exchanger, 18 is a medium-temperature sensible heat exchanger, 19 is a high-temperature sensible heat exchanger, 20 is a hot salt pump, 21 is a hot salt valve, 22 is a low-temperature heater, 23 is a medium-temperature heater, 24 is a high-temperature heater, 25 is a low-temperature heating valve for an energy storage system, 26 is a medium-temperature heating valve for an energy storage system, and 27 is a high-temperature heating valve for an energy storage system DETAILED DESCRIPTION

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, a cogeneration peak-shaving system with steam sensible heat cascade storage includes a cogeneration unit and a molten salt energy storage system; the cogeneration unit includes a boiler 1, a turbine high-pressure cylinder 2, a turbine medium- and low-pressure cylinders 3, a condenser 4, a condensate pump 5, a deaerator 6, a feed water pump 7, a high-pressure regenerator 8, a high-temperature heating valve 9, a medium-temperature heating valve 10, a low-temperature heating valve 11 and a heating feed water valve 12; the main steam outlet of the boiler 1 is connected to the inlet of the turbine high-pressure cylinder 2, the outlet of the turbine high-pressure cylinder 2 is connected to the reheat steam inlet of the boiler 1, the reheat steam outlet of the boiler 1 is connected to the inlet of the turbine medium- and low-pressure cylinders 3, the outlet of the turbine medium- and low-pressure cylinders 3 is connected to the inlet of the condenser 4, the outlet of the condenser 4 is connected to the inlet of the condensate pump 5, the outlet of the condensate pump 5 is connected to the inlet of the deaerator 6, the outlet of the deaerator 6 is connected to the feed water inlet of the high-pressure regenerator 8, and the feed water outlet of the high-pressure regenerator 8 is connected to the feed water inlet of the boiler 1;

[0021] The molten salt energy storage system comprises a cold salt tank 13, a hot salt tank 14, a cold salt pump 15, a cold salt valve 16, a low-temperature sensible heat exchanger 17, a medium-temperature sensible heat exchanger 18, a high-temperature sensible heat exchanger 19, a hot salt pump 20, a hot salt valve 21, a low-temperature heater 22, a medium-temperature heater 23, a high-temperature heater 24, a low-temperature heating valve 25 of the energy storage system, a medium-temperature heating valve 26 of the energy storage system, and a high-temperature heating valve 27 of the energy storage system; the outlet of the cold salt tank 13 is connected to the inlet of the cold salt pump 15, the outlet of the cold salt pump 15 is connected to the inlet of the cold salt valve 16, the outlet of the cold salt valve 16 is connected to the inlet of the molten salt side of the low-temperature sensible heat exchanger 17, the outlet of the low-temperature sensible heat exchanger 17 is connected to the molten salt side of the medium-temperature sensible heat exchanger 18, and the outlet of the low-temperature sensible heat exchanger 17 is connected to the molten salt side of the medium-temperature sensible heat exchanger 18. The heat exchanger 18 is connected to the molten salt side inlet, the medium-temperature sensible heat exchanger 18 molten salt side outlet is connected to the high-temperature sensible heat exchanger 19 molten salt side inlet, and the high-temperature sensible heat exchanger 19 molten salt side outlet is connected to the hot salt tank 14 inlet; the hot salt tank 14 outlet is connected to the hot salt pump 20 inlet, the hot salt pump 20 outlet is connected to the hot salt valve 21 inlet, the hot salt valve 21 outlet is connected to the molten salt side inlet of the low-temperature heater 22, the molten salt side outlet of the low-temperature heater 22 is connected to the molten salt side inlet of the medium-temperature heater 23, the molten salt side outlet of the medium-temperature heater 23 is connected to the molten salt side inlet of the high-temperature heater 24, and the molten salt side outlet of the high-temperature heater 24 is connected to the cold salt tank 13 inlet;

[0022] The coupling connection relationship between the cogeneration unit and the molten salt energy storage system is as follows:

[0023] The main steam outlet of boiler 1 is connected to the steam side inlet of high temperature sensible heat exchanger 19 through high temperature heating valve 9; the outlet of high pressure cylinder 2 is connected to the steam side inlet of medium temperature sensible heat exchanger 18 through medium temperature heating valve 10; the steam extraction port of medium and low pressure cylinder 3 is connected to the steam side inlet of low temperature sensible heat exchanger 17 through low temperature heating valve 11; the steam sides of low temperature sensible heat exchanger 17, medium temperature sensible heat exchanger 18 and high temperature sensible heat exchanger 19 are connected to low temperature heat users, medium temperature heat users and high temperature heat users respectively;

[0024] The outlet of the feed water pump 7 is connected to the steam side inlet of the low-temperature heater 22 of the molten salt energy storage system through the heating water supply valve 12. The steam side outlet of the low-temperature heater 22 is connected to the steam side inlet of the medium-temperature heater 23 and the inlet of the low-temperature heating valve 25 of the energy storage system. The steam side outlet of the medium-temperature heater 23 is connected to the steam side inlet of the high-temperature heater 24 and the inlet of the medium-temperature heating valve 26 of the energy storage system. The steam side outlet of the high-temperature heater 24 is connected to the inlet of the high-temperature heating valve 27 of the energy storage system.

[0025] The working method of the cogeneration peak-shaving system with a steam sensible heat cascade storage is as follows: steam is supplied from the high-pressure cylinder 2 of the steam turbine and the medium- and low-pressure cylinders 3 of the steam turbine to high-temperature heat users, medium-temperature heat users, and low-temperature heat users; before being supplied to the heat users, part of the sensible heat of the steam is stored in the molten salt energy storage system through the high-temperature sensible heat exchanger 19, the medium-temperature sensible heat exchanger 18, and the low-temperature sensible heat exchanger 17, respectively, and after the sensible heat of the steam is stored, it is cooled to the heating temperature and then supplied to the heat users respectively; and when the molten salt is used to heat the water supply, the water supply is heated into low-temperature heating steam, medium-temperature heating steam, and high-temperature heating steam through the low-temperature heater 22, the medium-temperature heater 23, and the high-temperature heater 24 in turn, and is supplied to the heat users;

[0026] When the cogeneration unit is at waist load, the cogeneration unit stores heat; the high-temperature heating valve 9, the medium-temperature heating valve 10, and the low-temperature heating valve 11 are opened; the low-temperature heating steam, the medium-temperature heating steam, and the high-temperature heating steam respectively pass through the low-temperature sensible heat exchanger 17, the medium-temperature sensible heat exchanger 18, and the high-temperature sensible heat exchanger 19 to store a part of the sensible heat in the molten salt, thereby avoiding the loss of available energy due to the mixed cooling water; and the low-temperature salt is heated in stages through the low-temperature sensible heat exchanger 17, the medium-temperature sensible heat exchanger 18, and the high-temperature sensible heat exchanger 19 in turn, thereby reducing the heat exchange temperature difference;

[0027] When the cogeneration unit is in the peak regulation process, it is necessary to completely use the molten salt energy storage system for heat supply, so as to realize heat and electricity decoupling; at this time, close the high-temperature heating valve 9, the medium-temperature heating valve 10, and the low-temperature heating valve 11; open the heating water supply valve 12, and extract the deoxygenated and pressurized supercooled water from the deaerator 6 through the water supply pump 7, and heat it into low-temperature heating steam, medium-temperature heating steam, and high-temperature heating steam in turn through the low-temperature heater 22, the medium-temperature heater 23, and the high-temperature heater 24 to replace the steam extraction from the turbine to heat the heat users; the low-temperature steam is pressure-regulated by the low-temperature heating valve 25 of the energy storage system, the medium-temperature steam is pressure-regulated by the medium-temperature heating valve 26 of the energy storage system, and the high-temperature steam is pressure-regulated by the high-temperature heating valve 27 of the energy storage system, and the heat load is completely provided by the heat storage system.

[0028] The present invention stores the sensible heat of multiple steam streams in molten salt by configuring a molten salt energy storage system. During the peak regulation process, heat is supplied by the molten salt energy storage system to enhance thermal and electrical decoupling, thereby realizing the cascade utilization of molten salt energy storage.

Claims

1. A combined heat and power peak-shaving system with steam sensible heat cascade storage, characterized in that: Includes a combined heat and power unit and a molten salt energy storage system; The cogeneration unit comprises a boiler (1), a high-pressure cylinder of a steam turbine (2), a medium- and low-pressure cylinder of a steam turbine (3), a condenser (4), a condensate pump (5), a deaerator (6), a feed water pump (7), a high-pressure regenerator (8), a high-temperature heating valve (9), a medium-temperature heating valve (10), a low-temperature heating valve (11) and a heating feed water valve (12); the main steam outlet of the boiler (1) is connected to the inlet of the high-pressure cylinder of the steam turbine (2), and the outlet of the high-pressure cylinder of the steam turbine (2) is connected to the boiler (1). The hot steam inlet is connected, the reheat steam outlet of the boiler (1) is connected to the inlet of the medium and low pressure cylinder (3) of the steam turbine, the outlet of the medium and low pressure cylinder (3) of the steam turbine is connected to the inlet of the condenser (4), the outlet of the condenser (4) is connected to the inlet of the condensate pump (5), the outlet of the condensate pump (5) is connected to the inlet of the deaerator (6), the outlet of the deaerator (6) is connected to the feed water inlet of the high pressure regenerator (8) through the feed water pump (7), and the feed water outlet of the high pressure regenerator (8) is connected to the feed water inlet of the boiler (1); The molten salt energy storage system comprises a cold salt tank (13), a hot salt tank (14), a cold salt pump (15), a cold salt valve (16), a low-temperature sensible heat exchanger (17), a medium-temperature sensible heat exchanger (18), a high-temperature sensible heat exchanger (19), a hot salt pump (20), a hot salt valve (21), a low-temperature heater (22), a medium-temperature heater (23), a high-temperature heater (24), a low-temperature heating valve (25) of the energy storage system, a medium-temperature heating valve (26) of the energy storage system, and a high-temperature heating valve (27) of the energy storage system; the outlet of the cold salt tank (13) is connected to the inlet of the cold salt pump (15), the outlet of the cold salt pump (15) is connected to the inlet of the cold salt valve (16), the outlet of the cold salt valve (16) is connected to the inlet of the molten salt side of the low-temperature sensible heat exchanger (17), and the outlet of the low-temperature sensible heat exchanger (17) is connected to the molten salt side of the molten salt side. The outlet of the medium-temperature sensible heat exchanger (18) is connected to the inlet of the molten salt side of the medium-temperature sensible heat exchanger (18), the outlet of the molten salt side of the medium-temperature sensible heat exchanger (18) is connected to the inlet of the molten salt side of the high-temperature sensible heat exchanger (19), and the outlet of the molten salt side of the high-temperature sensible heat exchanger (19) is connected to the inlet of the hot salt tank (14); the outlet of the hot salt tank (14) is connected to the inlet of the hot salt pump (20), the outlet of the hot salt pump (20) is connected to the inlet of the hot salt valve (21), the outlet of the hot salt valve (21) is connected to the inlet of the molten salt side of the low-temperature heater (22), the outlet of the molten salt side of the low-temperature heater (22) is connected to the inlet of the molten salt side of the medium-temperature heater (23), the outlet of the molten salt side of the medium-temperature heater (23) is connected to the inlet of the molten salt side of the high-temperature heater (24), and the outlet of the molten salt side of the high-temperature heater (24) is connected to the inlet of the cold salt tank (13); The coupling connection relationship between the cogeneration unit and the molten salt energy storage system is as follows: The main steam outlet of the boiler (1) is connected to the steam side inlet of the high-temperature sensible heat exchanger (19) through a high-temperature heating valve (9); the outlet of the high-pressure cylinder (2) is connected to the steam side inlet of the medium-temperature sensible heat exchanger (18) through a medium-temperature heating valve (10); the steam extraction port of the medium-low pressure cylinder (3) is connected to the steam side inlet of the low-temperature sensible heat exchanger (17) through a low-temperature heating valve (11); the steam sides of the low-temperature sensible heat exchanger (17), the medium-temperature sensible heat exchanger (18) and the high-temperature sensible heat exchanger (19) are connected to the low-temperature heat user, the medium-temperature heat user and the high-temperature heat user respectively; The outlet of the water supply pump (7) is connected to the steam side inlet of the low-temperature heater (22) of the molten salt energy storage system through the heating water supply valve (12); the steam side outlet of the low-temperature heater (22) is connected to the steam side inlet of the medium-temperature heater (23) and the inlet of the low-temperature heating valve (25) of the energy storage system; the steam side outlet of the medium-temperature heater (23) is connected to the steam side inlet of the high-temperature heater (24) and the inlet of the medium-temperature heating valve (26) of the energy storage system; and the steam side outlet of the high-temperature heater (24) is connected to the inlet of the high-temperature heating valve (27) of the energy storage system.

2. The working method of a combined heat and power peak-shaving system with cascaded storage of steam sensible heat according to claim 1, characterized in that: Steam is supplied from the high-pressure cylinder (2) of the steam turbine and the medium- and low-pressure cylinders (3) of the steam turbine to high-temperature heat users, medium-temperature heat users, and low-temperature heat users; before being supplied to the heat users, part of the sensible heat of the steam is stored in the molten salt energy storage system through the high-temperature sensible heat exchanger (19), the medium-temperature sensible heat exchanger (18), and the low-temperature sensible heat exchanger (17), respectively; after the sensible heat of the steam is stored, the temperature is reduced to the heating temperature and then supplied to the heat users; when the molten salt is used to heat the feed water, the feed water is heated into low-temperature heating steam, medium-temperature heating steam, and high-temperature heating steam through the low-temperature heater (22), the medium-temperature heater (23), and the high-temperature heater (24) in turn, and supplied to the heat users; When the cogeneration unit is at mid-load, the cogeneration unit stores heat; the high-temperature heating valve (9), the medium-temperature heating valve (10), and the low-temperature heating valve (11) are opened; the low-temperature heating steam, the medium-temperature heating steam, and the high-temperature heating steam respectively store a portion of sensible heat in the molten salt through the low-temperature sensible heat exchanger (17), the medium-temperature sensible heat exchanger (18), and the high-temperature sensible heat exchanger (19); and the low-temperature salt is heated in stages through the low-temperature sensible heat exchanger (17), the medium-temperature sensible heat exchanger (18), and the high-temperature sensible heat exchanger (19); When the cogeneration unit is in the peak regulation process, it is necessary to completely supply heat through the molten salt energy storage system to achieve heat and electricity decoupling; at this time, the high-temperature heating valve (9), the medium-temperature heating valve (10), and the low-temperature heating valve (11) are closed; the heating water supply valve (12) is opened, and the deoxygenated and pressurized supercooled water is extracted from the deaerator (6) through the water supply pump (7), and is successively heated by the low-temperature heater (22), the medium-temperature heater (23), and the high-temperature heater (24) into low-temperature heating steam, medium-temperature heating steam, and high-temperature heating steam to replace the steam extracted from the steam turbine to supply heat to the heat users; the low-temperature steam is regulated by the low-temperature heating valve (25) of the energy storage system, the medium-temperature steam is regulated by the medium-temperature heating valve (26) of the energy storage system, and the high-temperature steam is regulated by the high-temperature heating valve (27) of the energy storage system, and the heat load is completely provided by the heat storage system.

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