A steam sensible heat cascade storage combined heat and power peak shaving system and working method

Abstract

The application discloses a combined heat and power peak shaving system with steam sensible heat cascade storage and a working method thereof. Steam is supplied to high-temperature heat users, medium-temperature heat users and low-temperature heat users from a high-pressure cylinder of a steam turbine and a low-pressure cylinder of the steam turbine. Before being supplied to the heat users, the steam is partially 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. After the sensible heat of the steam is stored, the temperature of the steam is reduced to the heat supply temperature, and then the steam is supplied to the heat users. When the molten salt is heated to supply water, the 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, and then the water is supplied to the heat users. According to the application, the molten salt energy storage system is configured to store the sensible heat of multiple steam streams in the molten salt to reduce the temperature, and the molten salt is heated in stages. When the combined heat and power unit is in peak shaving, the molten salt is released, the heat is completely supplied through the molten salt energy storage system, and the combined heat and power is completely decoupled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of improving the peak regulation capacity of coal-fired cogeneration units, and particularly relates to a steam sensible heat cascade storage cogeneration peak regulation system and a working method. BACKGROUND

[0002] At present, with large-scale grid connection of new energy, the proportion of new energy power generation is becoming higher and higher. However, due to the large variation of new energy supply with time, the daily energy production of new energy cannot be effectively predicted at present, so the supply and demand balance of the power grid side will be destroyed, and the power supply of the power grid will be affected. The coal-fired unit has certain flexibility in participating in peak regulation and frequency modulation, therefore, improving the peak regulation capacity of the coal-fired cogeneration unit is an effective solution. At present, there are mainly coupling energy storage systems, low-pressure cylinder zero output and other peak regulation means. However, the steam heat storage of the coupling energy storage system has the problems of large heat exchange temperature difference and large system available energy loss, which causes low operation efficiency of the energy storage system and affects the economy of operation. At the same time, the temperature regulation of the traditional heating steam is realized by using desuperheating water, and the available energy of the heating steam is greatly lost, and in the case of multiple heat users, the energy utilization rate is low. SUMMARY

[0003] To solve the above problems, the purpose of the present application is to provide a steam sensible heat cascade storage cogeneration peak regulation system and a working method. The present application configures a molten salt energy storage system to store the sensible heat of multiple steam in the molten salt to reduce the temperature, thereby avoiding the use of desuperheating water to control the heating temperature. At the same time, the molten salt is heated in stages to reduce the heat exchange temperature difference. When the cogeneration unit is peak-regulated, the molten salt is released, and the molten salt energy storage system is used to completely heat, thereby achieving the purpose of complete decoupling of heat and electricity.

[0004] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0005] A steam sensible heat cascade storage cogeneration peak regulation system, comprising a cogeneration unit and a molten salt energy storage system.

[0006] The cogeneration unit comprises a boiler 1, a high-pressure cylinder 2 of a steam turbine, a medium-low pressure cylinder 3 of a steam turbine, a condenser 4, a condensate pump 5, a deaerator 6, a feedwater 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 feedwater valve 12. The main steam outlet of the boiler 1 is connected with the inlet of the high-pressure cylinder 2 of the steam turbine, the outlet of the high-pressure cylinder 2 of the steam turbine is connected with the reheated steam inlet of the boiler 1, the reheated steam outlet of the boiler 1 is connected with the inlet of the medium-low pressure cylinder 3 of the steam turbine, the outlet of the medium-low pressure cylinder 3 of the steam turbine is connected with the inlet of the condenser 4, the outlet of the condenser 4 is connected with the inlet of the condensate pump 5, the outlet of the condensate pump 5 is connected with the inlet of the deaerator 6, the outlet of the deaerator 6 is connected with the feedwater inlet of the high-pressure regenerator 8, and the feedwater outlet of the high-pressure regenerator 8 is connected with the feedwater 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, an energy storage system low-temperature heat supply valve 25, an energy storage system medium-temperature heat supply valve 26, an energy storage system high-temperature heat supply valve 27; 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 molten salt side of the low-temperature sensible heat exchanger 17 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;

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

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

[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 heat supply feed water 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 energy storage system low-temperature heat supply valve 25, 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 energy storage system medium-temperature heat supply valve 26, and the steam side outlet of the high-temperature heater 24 is connected to the inlet of the energy storage system high-temperature heat supply valve 27.

[0011] The working method of the combined heat and power peak shaving system with steam sensible heat cascade storage, steam from the high-pressure cylinder 2 of the steam turbine and the medium and low-pressure cylinder 3 of the steam turbine supplies heat to high-temperature heat users, medium-temperature heat users and low-temperature heat users; before being delivered to the heat users, the steam is partially stored into 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 steam sensible heat is stored and the temperature is reduced to the heat supply temperature, the steam is delivered to the heat users respectively; when the molten salt heats the feed water, the feed water is heated into low-temperature heat supply steam, medium-temperature heat supply steam and high-temperature heat supply steam through the low-temperature heater 22, the medium-temperature heater 23 and the high-temperature heater 24 in turn and is delivered to the heat users.

[0012] When the combined heat and power unit is in the waist load, the combined heat and power unit stores heat; the high-temperature heat supply valve 9, the medium-temperature heat supply valve 10 and the low-temperature heat supply valve 11 are opened; the low-temperature heat supply steam, the medium-temperature heat supply steam and the high-temperature heat supply steam store part of the sensible heat into 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 respectively, so that the available energy loss caused by the mixed desuperheating water is avoided; 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, so that the heat exchange temperature difference is reduced.

[0013] When the combined heat and power unit is in the peak shaving process, the heat supply needs to be completely realized by the molten salt energy storage system, so that the heat and electricity are decoupled; at this time, the high-temperature heat supply valve 9, the medium-temperature heat supply valve 10 and the low-temperature heat supply valve 11 are closed; the heat supply feed water valve 12 is opened; the deaerated and pressurized subcooled water in the deaerator 6 is extracted, is deaerated, is heated in stages through the low-temperature heater 22, the medium-temperature heater 23 and the high-temperature heater 24 in turn and becomes low-temperature heat supply steam, medium-temperature heat supply steam and high-temperature heat supply steam to replace the steam extraction from the steam turbine to supply heat to the heat users; the low-temperature steam is adjusted in pressure through the energy storage system low-temperature heat supply valve 25, the medium-temperature steam is adjusted in pressure through the energy storage system medium-temperature heat supply valve 26 and the high-temperature steam is adjusted in pressure through the energy storage system high-temperature heat supply valve 27, and the heat load is completely provided by the heat storage system.

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

[0015] (1) The present application designs the molten salt energy storage system to store the sensible heat of multiple steam in the molten salt to reduce the temperature, so that the heat supply temperature is controlled without desuperheating water, and the available energy loss of the heat supply steam is reduced.

[0016] (2) In the present application, the cascade heat exchange is realized according to the temperature of the cold and hot fluids in the process of heating and heat release of the molten salt, the heat exchange temperature difference is reduced, the purpose of energy cascade utilization is achieved, and the economy of the operation of the molten salt energy storage system is increased. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 This is a schematic diagram of the cogeneration peak-shaving system for steam sensible heat cascade storage according to the present invention.

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

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

[0020] like Figure 1 As shown, a cogeneration peak-shaving system with sensible heat storage includes a cogeneration unit and a molten salt energy storage system. The cogeneration unit includes a boiler 1, a high-pressure cylinder 2 of a steam turbine, a medium- and low-pressure cylinder 3 of a steam turbine, a condenser 4, a condensate pump 5, a deaerator 6, a feedwater 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 feedwater valve 12. The main steam outlet of the boiler 1 is connected to the inlet of the high-pressure cylinder 2 of the steam turbine, the outlet of the high-pressure cylinder 2 of the steam turbine 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 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 feedwater inlet of the high-pressure regenerator 8, and the feedwater outlet of the high-pressure regenerator 8 is connected to the feedwater 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, an energy storage system low-temperature heat supply valve 25, an energy storage system medium-temperature heat supply valve 26, an energy storage system high-temperature heat supply valve 27; the outlet of the cold salt tank 13 is connected with the inlet of the cold salt pump 15, the outlet of the cold salt pump 15 is connected with the inlet of the cold salt valve 16, the outlet of the cold salt valve 16 is connected with the inlet of the molten salt side of the low-temperature sensible heat exchanger 17, the outlet of the molten salt side of the low-temperature sensible heat exchanger 17 is connected with 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 with 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 with the inlet of the hot salt tank 14; the outlet of the hot salt tank 14 is connected with the inlet of the hot salt pump 20, the outlet of the hot salt pump 20 is connected with the inlet of the hot salt valve 21, the outlet of the hot salt valve 21 is connected with 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 with 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 with 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 with the inlet of the cold salt tank 13;

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

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

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

[0025] The working method of the combined heat and power peak shaving system with steam sensible heat cascade storage, steam from the high-pressure cylinder 2 of the steam turbine and the medium and low-pressure cylinder 3 of the steam turbine supplies heat to high-temperature heat users, medium-temperature heat users and low-temperature heat users; before being delivered to the heat users, the steam is partially stored into 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 steam sensible heat is stored and the temperature is lowered to the heat supply temperature, the steam is delivered to the heat users respectively; when the molten salt heats the feed water, the feed water is heated into low-temperature heat supply steam, medium-temperature heat supply steam and high-temperature heat supply steam through the low-temperature heater 22, the medium-temperature heater 23 and the high-temperature heater 24 in turn and is delivered to the heat users;

[0026] When the combined heat and power unit is in the waist load, the combined heat and power unit stores heat; the high-temperature heat supply valve 9, the medium-temperature heat supply valve 10 and the low-temperature heat supply valve 11 are opened; the low-temperature heat supply steam, the medium-temperature heat supply steam and the high-temperature heat supply steam store part of the sensible heat into 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 respectively, so that the available energy loss caused by the mixed desuperheating water is avoided; 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, so that the heat exchange temperature difference is reduced;

[0027] When the combined heat and power unit is in the peak shaving process, the heat supply needs to be completely realized through the molten salt energy storage system, so as to realize heat and electricity decoupling; at this time, the high-temperature heat supply valve 9, the medium-temperature heat supply valve 10 and the low-temperature heat supply valve 11 are closed; the heat supply feed water valve 12 is opened; the supercooled water extracted from the deaerator 6 after deaeration and pressurization is heated in stages through the low-temperature heater 22, the medium-temperature heater 23 and the high-temperature heater 24 into low-temperature heat supply steam, medium-temperature heat supply steam and high-temperature heat supply steam to replace the steam extracted from the steam turbine to supply heat to the heat users; the low-temperature steam is adjusted in pressure through the energy storage system low-temperature heat supply valve 25, the medium-temperature steam is adjusted in pressure through the energy storage system medium-temperature heat supply valve 26, and the high-temperature steam is adjusted in pressure through the energy storage system high-temperature heat supply valve 27, and the heat load is completely provided by the heat storage system.

[0028] The present application stores the sensible heat of multiple steam in the molten salt through the molten salt energy storage system, and in the peak shaving process, the heat supply is realized through the molten salt energy storage system, so as to realize heat and electricity decoupling and further realize the cascade utilization of the molten salt energy storage.

Claims

1. A method for operating a cogeneration peak-shaving system with cascaded steam sensible heat storage, characterized in that: The system includes a combined heat and power unit and a molten salt energy storage system; The combined heat and power (CHP) unit includes a boiler (1), a high-pressure turbine cylinder (2), a medium- and low-pressure turbine cylinder (3), a condenser (4), a condensate pump (5), a deaerator (6), a feedwater 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 feedwater valve (12); the main steam outlet of the boiler (1) is connected to the inlet of the high-pressure turbine cylinder (2), and the outlet of the high-pressure turbine cylinder (2) is connected to the boiler (1) regenerator. The hot steam inlet is connected, the reheat steam outlet of the boiler (1) is connected to the inlet of the low-pressure cylinder (3) of the steam turbine, the outlet of the 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 includes 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), a medium-temperature heating valve (26), and a high-temperature heating valve (27). 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 molten salt side inlet 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 inlet. The outlet is connected to the molten salt side inlet of the medium-temperature sensible heat exchanger (18), the molten salt side outlet of the medium-temperature sensible heat exchanger (18) is connected to the molten salt side inlet of the high-temperature sensible heat exchanger (19), the molten salt side outlet 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 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 inlet of the cold salt tank (13); The coupling connection between the combined heat and power unit and the molten salt energy storage system is as follows: The main steam outlet of the boiler (1) is connected to the steam inlet of the high-temperature sensible heat exchanger (19) via the high-temperature heating valve (9); the outlet of the high-pressure cylinder (2) is connected to the steam inlet of the medium-temperature sensible heat exchanger (18) via the medium-temperature heating valve (10); the extraction port of the medium-low pressure cylinder (3) is connected to the steam inlet of the low-temperature sensible heat exchanger (17) via the 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 respectively connected to low-temperature heat users, medium-temperature heat users, and high-temperature heat users; The outlet of the water pump (7) is connected to the steam inlet of the low-temperature heater (22) of the molten salt energy storage system through the heating water supply valve (12). The steam outlet of the low-temperature heater (22) is connected to the steam inlet of the medium-temperature heater (23) and the inlet of the low-temperature heating valve (25) of the energy storage system. The steam outlet of the medium-temperature heater (23) is connected to the steam inlet of the high-temperature heater (24) and the inlet of the medium-temperature heating valve (26) of the energy storage system. The steam outlet of the high-temperature heater (24) is connected to the inlet of the high-temperature heating valve (27) of the energy storage system. The working method is as follows: Steam is supplied from the high-pressure cylinder (2) and the medium-low pressure cylinder (3) of the steam turbine to high-temperature heat users, medium-temperature heat users, and low-temperature heat users; before being delivered to the heat users, the steam is partially 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 storing the sensible heat of the steam, it is cooled down to the heating temperature and then delivered to the heat users; when the molten salt heats the heating feedwater, it 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 sequence and delivered to the heat users. When the cogeneration unit is under low 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 portion of the sensible heat into the molten salt; while 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); During the peak shaving process of the cogeneration unit, it is necessary to supply heat entirely through the molten salt energy storage system to achieve heat and electricity decoupling. At this time, the high temperature heating valve (9), medium temperature heating valve (10), and low temperature heating valve (11) are closed. The heating feedwater valve (12) is opened, and the deaerated and pressurized subcooled water is drawn from the deaerator (6) through the feedwater pump (7). It is then heated in stages through the low temperature heater (22), medium temperature heater (23), and high temperature heater (24) to become low temperature heating steam, medium temperature heating steam, and high temperature heating steam to replace the steam extracted from the turbine to supply heat to the 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. The heat load is entirely provided by the heat storage system.

Images