Heat supply and power generation system coupled with molten salt heat storage and capable of improving thermoelectricity load flexibility and operation method

Abstract

The invention belongs to the field of coal-fired power generation, and particularly relates to a heat supply and power generation system for improving the flexibility of a thermoelectric load by coupling molten salt heat storage and an operation method, the system is additionally provided with a heat supply network heating system on the basis of a conventional coal-fired power generation system, and is coupled with an innovative heat storage system adopting a collaborative heat storage and collaborative heat release structure. When the power supply load of the coupling heat supply power generation system is reduced, reheated steam and redundant electric power which is not connected to the network are used for heating molten salt for collaborative heat storage, meanwhile, reheated cold section extraction steam is used for supplying heat to a heat supply network, the load reduction rate is increased, the downward peak regulation depth of the coupling heat supply power generation system can be effectively reduced, and the power supply efficiency is improved. And zero power output of the power generation system can be realized under the condition that the boiler maintains the lowest operation load. The thermoelectric load characteristic interval range of the coupling heat supply power generation system is remarkably expanded, the variable load rate of the coupling heat supply power generation system is improved, and the heat supply and power supply flexibility of the coupling heat supply power generation system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of coal-fired power generation, and in particular relates to a heat supply and power generation system and an operation method for coupling molten salt heat storage to improve the flexibility of thermal power load. Background Art

[0002] In the context of vigorously promoting the development of renewable energy, the coal-fired power generation system has changed from the main power supply mode to the peak load mode, and the power market has higher requirements for the heat and power supply load boundary of the coal-fired system. As a device that can store and release energy for a long time, the thermal storage system has high operating efficiency and stability.

[0003] Since the boiler load change rate is limited and the operating stability is poor under low load conditions, the flexibility and load expansion capacity of the heating and power generation system are limited. Therefore, it is necessary to consider coupling energy storage equipment and transform the heating and power generation system. In coal-fired power plants equipped with heat storage systems, electric heating, main steam, reheated steam, intermediate stage extraction and flue gas heat are often used to heat the heat storage system to improve the flexibility and peak-shaving capacity of cogeneration. In response to these coupling methods, multiple studies have proposed different optimization measures, such as optimizing the extraction position, return water position and heat storage tank capacity to improve the thermal performance and economic benefits of the system. Studies have shown that by selecting the appropriate extraction position, using reheated steam extraction and returning steam to the low-pressure cylinder, the best economy can be achieved, while main steam extraction is superior in improving system flexibility. In addition, the optimal design of the heat storage tank size can effectively improve the annual efficiency of the system and reduce carbon dioxide emissions. The performance comparison results of different thermal and electric decoupling schemes show that the heat storage tank decoupling method is the most effective in reducing the minimum load.

[0004] Although the existing thermal storage coupling methods have improved the flexibility of the heating and power generation system to a certain extent, these technologies still have some obvious disadvantages. First, although the electric heating method can provide rapid heating, its high energy consumption will lead to energy waste; second, the main steam extraction pressure is relatively high, and direct use for heating the thermal storage system will result in large heat losses; in addition, due to temperature restrictions, reheated steam and intermediate stage extraction can only store limited heat, and the use of flue gas heat requires the transformation of the existing boiler system, which requires a large investment. Therefore, these technologies are still limited in the maximum boundaries of expanding the heating and power supply load, and it is difficult to meet the needs of high load fluctuations and large-scale applications. Summary of the invention

[0005] In view of the defects or improvement needs of the prior art, the purpose of the present invention is to provide a heat supply and power generation system and an operation method for coupling molten salt heat storage to improve the flexibility of thermal power load; when the coupled heat supply and power generation system reduces the power supply load, the reheated steam and the excess power not connected to the grid are used to heat the molten salt for synergistic heat storage, and the reheated cold section extraction steam is used to supply heat to the heat network, which effectively reduces the depth of the downward peak regulation of the coupled heat supply and power generation system, and can achieve zero power output of the power generation system under the condition that the boiler maintains the minimum operating load, thereby improving its load change rate. When the coupled heat supply and power generation system increases the power supply load, the high-temperature molten salt is divided into three parts by a diverter valve while keeping the boiler heat load unchanged, one part is used to increase the boiler feed water temperature, one part is used to produce the amount of superheated steam required to increase the power generation load, and the remaining part of the high-temperature molten salt is used to supply heat to the heat network, thereby improving the load increase rate and heating load of the coupled heat supply and power generation system. By coupling an innovative heat storage system that adopts a synergistic heat storage and synergistic heat release structure, the range of the thermal power load characteristics of the coupled heat supply and power generation system is significantly expanded, the load change rate of the coupled heat supply and power generation system is improved, and the flexibility of its heating and power supply is improved.

[0006] The present invention is implemented as follows: a heat supply and power generation system coupled with molten salt heat storage to improve the flexibility of thermal power loads, comprising a coal-fired power generation system, a molten salt cooperative heat storage system coupled thereto, and a heating network heating system;

[0007] The coal-fired power generation system comprises a boiler (1), a high-pressure cylinder of a steam turbine (2), a diverter valve (3), a diverter valve (4), a medium-pressure cylinder of a steam turbine (5), a low-pressure cylinder of a steam turbine (6), a generator (7), a condenser (8), a condensate pump (9), a low-pressure heater (10), a deaerator (11), a feedwater pump (12), a high-pressure heater (13), a diverter valve (14), a mixing valve (15), a diverter valve (16), a mixing valve (17), a diverter valve (18), and a mixing valve (19); the main steam outlet of the boiler (1) is connected to the inlet of the mixing valve (17), and the outlet of the mixing valve (17) is connected to the steam inlet of the high-pressure cylinder of the steam turbine (2); the extraction steam outlet of the high-pressure cylinder of the steam turbine (2) is connected to the extraction steam inlet of the high-pressure heater (13). The steam outlet of the high-pressure cylinder (2) of the steam turbine is connected to the inlet of the diverter valve (3); the diverter valve (3) divides the steam into two paths, one of which is connected to the inlet of the diverter valve (4) and the other is connected to the extraction steam inlet of the high-pressure heater (13); the diverter valve (4) divides the steam into two paths, one of which is connected to the reheat steam inlet of the boiler (1) and the other is connected to the steam inlet of the heat supply heat exchanger (38); the reheat steam outlet of the boiler (1) is connected to the inlet of the diverter valve (18); the diverter valve (18) divides the reheat steam into two paths, one of which enters the intermediate-pressure cylinder (5) of the steam turbine and the other enters the heat storage heat exchanger (20) in the heat storage circuit of the molten salt cooperative heat storage system; the extraction steam outlet of the intermediate-pressure cylinder (5) of the steam turbine is connected to the high-pressure heater (13) and the deaerator (1 1), the steam outlet of the intermediate pressure cylinder (5) of the steam turbine is connected to the mixing valve (19); the outlet of the mixing valve (19) is connected to the steam inlet of the low pressure cylinder (6) of the steam turbine; the steam extraction of the low pressure cylinder (6) of the steam turbine is connected to the low pressure heater (10), the steam outlet of the low pressure cylinder (6) of the steam turbine is connected to the steam inlet of the condenser (8); the condensate outlet of the condenser (8) is connected to the inlet of the condensate pump (9); the outlet of the condensate pump (9) is connected to the water working medium inlet of the low pressure heater (10); the water working medium outlet of the low pressure heater (10) is connected to the water working medium inlet of the deaerator (11), the drain outlet of the low pressure heater (10) is connected to the drain inlet of the condenser (8); the water working medium outlet of the deaerator (11) is connected to the feed water The inlet of the water pump (12) is connected; the outlet of the water pump (12) is connected to the water working medium inlet of the high-pressure heater (13); the water working medium outlet of the high-pressure heater (13) is connected to the diverter valve (14), and the drain outlet of the high-pressure heater (13) is connected to the drain inlet of the deaerator (11); the diverter valve (14) divides the water working medium into two parts, one part enters the water working medium inlet of the low-temperature heat exchanger (20) of the heat release loop of the molten salt storage cooperative heat storage system, and the other part enters the water feeding inlet of the water mixing valve (15); the outlet of the water mixing valve (15) is connected to the diverter valve (16); the diverter valve (16) divides the water working medium into two parts, one part enters the water working medium inlet of the high-temperature preheater (26), and the other part enters the water feeding inlet of the boiler (1);The steam turbine high-pressure cylinder (2), the steam turbine intermediate-pressure cylinder (5) and the steam turbine low-pressure cylinder (6) are connected via a rotating shaft and jointly drive a generator (7) to output electrical power externally;

[0008] The heat storage circuit of the molten salt collaborative heat storage system comprises a high-temperature heat storage tank (24), a low-temperature heat storage tank (25), a heat storage heat exchanger (20), an electric heater (21), an electric heater (22), a mixing valve (23), and a diverter valve (26); the outlet of the low-temperature heat storage tank (25) is connected to the inlet of the diverter valve (26); the diverter valve (26) divides the low-temperature molten salt into two paths, one leading to the molten salt inlet of the heat storage heat exchanger (20), and the other leading to the molten salt inlet of the electric heater (22); the molten salt outlet of the heat storage heat exchanger (20) is connected to the inlet of the electric heater (21), and the steam outlet of the heat storage heat exchanger (20) is connected to the steam inlet of the mixing valve (19); the molten salt outlet of the electric heater (22) is connected to the inlet of the mixing valve (23); the molten salt outlet of the electric heater (21) is connected to the inlet of the mixing valve (23); the outlet of the mixing valve (23) is connected to the inlet of the high-temperature heat storage tank (24);

[0009] The heat release circuit of the molten salt collaborative heat storage system comprises a high-temperature heat storage tank (24), a low-temperature heat storage tank (25), a diverter valve (14), a low-temperature heat release heat exchanger (31), a mixing valve (20), a diverter valve (16), a high-temperature heat release preheater (27), a high-temperature heat release evaporator (28), a high-temperature heat release superheater (29), a diverter valve (30), a mixing valve (32), a diverter valve (36), and a mixing valve (37); the molten salt outlet of the high-temperature heat storage tank (24) is connected to the inlet of the diverter valve (30), and the diverter valve (36) is connected to the mixing valve (37). The flow valve (30) divides the molten salt into three paths, one path leading to the inlet of the mixing valve (32), one path leading to the molten salt inlet of the high-temperature heat release superheater (29), and one path leading to the molten salt inlet of the low-temperature heat release heat exchanger (31); the molten salt outlet of the high-temperature heat release superheater (29) is connected to the molten salt inlet of the high-temperature heat release evaporator (28), the steam inlet of the high-temperature heat release superheater (29) is connected to the steam outlet of the high-temperature heat release evaporator (28), and the steam outlet of the high-temperature heat release superheater (29) is connected to the mixing valve (17). The molten salt outlet of the high-temperature heat release evaporator (28) is connected to the molten salt inlet of the high-temperature heat release preheater (27), and the steam inlet of the high-temperature heat release evaporator (28) is connected to the steam outlet of the high-temperature heat release preheater (27); the molten salt outlet of the high-temperature heat release preheater (27) is connected to the inlet of the mixing valve (32), and the water working medium inlet of the high-temperature heat release preheater (27) is connected to the feed water working medium outlet of the diverter valve (16); the molten salt outlet of the low-temperature heat release heat exchanger (31) is connected to the inlet of the mixing valve (32) The water medium inlet of the low-temperature heat release heat exchanger (31) is connected to the water supply outlet of the diverter valve (14), and the water medium outlet of the low-temperature heat release heat exchanger (31) is connected to the inlet of the mixing valve (15); the outlet of the mixing valve (32) is connected to the inlet of the diverter valve (36); the diverter valve (36) divides the molten salt into two paths, one leading to the molten salt inlet of the molten salt heat exchanger (34) of the heating network, and the other leading to the inlet of the mixer (37); the molten salt outlet of the mixer (37) is connected to the inlet of the low-temperature heat storage tank (25);

[0010] The molten salt heating heating network circuit of the heating network heating system comprises a heating network low-temperature water inlet (35), a heating network low-temperature water outlet (33), and a heating network molten salt heat exchanger (34); the molten salt inlet of the heating network molten salt heat exchanger (34) is connected to the outlet of the diverter valve (36), the molten salt outlet of the heating network molten salt heat exchanger (34) is connected to the inlet of the mixing valve (37), and the hot water inlet of the heating network molten salt heat exchanger (34) is connected to the low-temperature water inlet (35);

[0011] The steam heating network circuit of the heating network heating system comprises a heating network low-temperature water inlet (38), a heating network low-temperature water outlet (40), and a heating network steam heat exchanger (39); the hot water outlet of the heating network molten salt heat exchanger (34) is connected to the low-temperature water outlet (33); the steam inlet of the heating network steam heat exchanger (39) is connected to the outlet of the diverter valve (4), the steam outlet of the heating network steam heat exchanger (38) is connected to the condenser (8), the hot water inlet of the heating network steam heat exchanger (39) is connected to the low-temperature water inlet (38), and the hot water outlet of the heating network steam heat exchanger (39) is connected to the low-temperature water outlet (40).

[0012] Furthermore, the electric energy source of the electric heater (21) and the electric heater (22) is the electricity that cannot be connected to the grid during the deep peak regulation period of the coal-fired power generation system.

[0013] Furthermore, the high-temperature heat storage tank (24) is filled with high-temperature molten salt, and the low-temperature heat storage tank (25) is filled with low-temperature molten salt.

[0014] Another object of the present invention is to provide an operation method for improving the flexibility of thermal power load by coupling molten salt heat storage of a thermal power generation system based on the coupling molten salt heat storage to improve the flexibility of thermal power load, and the method is specifically as follows:

[0015] S1: When the electric load rate of the coupled heating and power generation system needs to remain unchanged, or its own variable load capacity can meet the load change requirements, and there is no need to store or release heat, and there is no need to provide heat for the heating system of the heating network, the coal-fired power generation system maintains its operating state and increases or decreases the water flow rate according to the load change requirements; the molten salt collaborative heat storage system does not store or release heat; the heating system of the heating network does not provide heat;

[0016] S2: When the electric load rate of the coupled heating and power generation system needs to remain unchanged, or its own variable load capacity can meet the load change requirements, and it is necessary to provide heat for the heating system of the heating network, the molten salt heating network loop is opened, the coal-fired power generation system maintains its operating state, and increases or decreases the water supply flow rate according to the load change requirements; the molten salt collaborative heat storage system does not store or release heat; in the heating system of the heating network, the molten salt at the outlet of the diverter valve (36) is adjusted to flow into the molten salt inlet of the molten salt heat exchanger (34) of the heating network, and the opening of the diverter valve (30) is adjusted to provide the molten salt mass flow rate required by the molten salt heat exchanger (34) of the heating network;

[0017] S3: When the coupled heating and power generation system needs to increase the power supply load and participate in the upward deep peak regulation, and does not need to provide heat for the heating system of the heating network, the heat release circuit of the heat storage system is opened. In the coal-fired power generation system, the opening of the diverter valve (14) is adjusted to increase the feed water temperature, and the opening of the diverter valve (16) is adjusted to heat part of the heated feed water into superheated steam through the high-temperature heat release preheater (27), the high-temperature heat release evaporator (28), and the high-temperature heat release superheater (29). At the same time, the feed water flow rate is increased to increase the power load rate of the coupled heating and power generation system, thereby realizing the improvement of the upward peak regulation depth of the coupled heating and power generation system. In the heat storage system, the molten salt at the outlet of the diverter valve (36) is adjusted to flow into the mixing valve (37). By adjusting the opening of the diverter valve (30), the feed water temperature at the outlet of the mixing valve (15) is adjusted to meet the working temperature requirements of the high-temperature heat release preheater (27), the high-temperature heat release evaporator (28), and the high-temperature heat release superheater (29); the heating system of the heating network does not provide heat.

[0018] S4: On this basis, when the heating system of the heating network changes its state and needs to be coupled to the heating power generation system to provide heat for it, the molten salt heat collection network loop is opened, and the molten salt at the outlet of the diverter valve (36) is adjusted to flow into the molten salt inlet of the molten salt heat exchanger (34) of the heating network, and the opening of the diverter valve (30) is adjusted to provide a molten salt mass flow rate required by the molten salt heat exchanger (34) of the heating network;

[0019] S5: When the coupled heating and power generation system needs to reduce the power supply load and participate in the downward deep peak regulation, and does not need to provide heat for the heating network heating system, the heat storage circuit of the heat storage system is opened. In the coal-fired power generation system, the opening of the diverter valve (18) is adjusted to reduce the power load rate of the coupled heating and power generation system; in the heat storage system, the power load rate of the coupled heating and power generation system is reduced by adjusting the electric heating power of the electric heater (22), so as to increase the downward peak regulation depth of the coupled heating and power generation system; the heating network heating system does not provide heat;

[0020] S6: On this basis, when the heating system of the heating network changes its state and needs to be coupled with the heating and power generation system to provide heat for it, the steam heating network circuit of the heating system of the heating network is opened, and the heating amount is adjusted by adjusting the opening of the diverter valve (4), while reducing the electric load rate of the coupled heating and power generation system.

[0021] Furthermore, the temperature of the low temperature tank is 295°C, and the temperature of the high temperature tank is 560°C.

[0022] Furthermore, the molten salt temperature at the outlet of the electric heater (21) and the electric heater (22) is 560°C.

[0023] Furthermore, in the heating network heating system, the mass flow rate of molten salt flowing through the heating network molten salt heat exchanger (34) is determined by the required mass flow rate of the heating network low-temperature water inlet (35), and the mass flow rate of steam flowing through the heating network steam heat exchanger (39) is determined by the required mass flow rate of the heating network low-temperature water inlet (38).

[0024] Furthermore, the total flow rate of the reheated steam diverted by the diverter valve (4) and the diverter valve (18) is limited by the minimum flow rate of the intermediate pressure cylinder (2) of the steam turbine and should not exceed 79% of the total flow rate of the reheated steam.

[0025] Furthermore, in the heat storage circuit of the molten salt collaborative heat storage system, the opening of the valve (26) is determined by the mass flow rate flowing through the heat storage heat exchanger (20) and the electric heating power of the electric heater (22).

[0026] Furthermore, the steam outlet temperature of the heat storage heat exchanger (20) should be kept the same as the steam outlet temperature of the intermediate pressure cylinder (5) of the steam turbine, and the temperature range is 339° C. to 354° C.

[0027] Furthermore, in the heat release circuit of the molten salt collaborative heat storage system, the opening degree of the valve (30) is determined by the mass flow rate flowing through the low-temperature heat release heat exchanger (31) and the high-temperature heat release superheater (29).

[0028] Furthermore, the maximum opening degree of the diverter valve (14) is 35%.

[0029] Furthermore, the temperature range of the steam at the outlet of the low-temperature heat release heat exchanger (31) is 224°C to 345°C.

[0030] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0031] First, the present invention couples a heat storage system in a heating and power generation system. When the coupled heating and power generation system reduces the power supply load, the reheated steam and excess electricity not connected to the grid are used to heat the molten salt for collaborative heat storage. At the same time, the reheated cold section steam extraction is used to supply heat to the heat network, which effectively reduces the depth of downward peak regulation of the coupled heating and power generation system, and can achieve zero electric power output of the power generation system under the condition that the boiler maintains the lowest operating load, thereby improving its load change rate.

[0032] When the coupled heating and power generation system increases the power supply load, while keeping the boiler heat load unchanged, the high-temperature molten salt is divided into three parts by a diverter valve. One part is used to increase the boiler feed water temperature, one part is used to produce the increased amount of superheated steam required to increase the power generation load, and the remaining part of the high-temperature molten salt is used to supply heat to the heating network, thereby improving the load increase rate and heating load of the coupled heating and power generation system.

[0033] By coupling an innovative heat storage system with a synergistic heat storage and synergistic heat release structure, the range of thermal and electric load characteristics of the coupled heating and power generation system is significantly expanded, the load variation rate of the coupled heating and power generation system is improved, and the flexibility of its heating and power supply is enhanced.

[0034] Second, the technical solution of the present invention fills the technical gap in the industry at home and abroad: the present invention proposes an innovative coupling design of a heat storage system and a heating unit, which significantly improves the load regulation capability and flexibility of traditional coal-fired heating and power generation systems through coordinated heat storage and coordinated heat release structures.

[0035] Compared with existing technologies at home and abroad, this technical solution fills the following gaps:

[0036] 1. Expansion of load regulation range: For the first time, a technological breakthrough of zero electric power output of the heating and power generation system was achieved while the boiler maintained the minimum operating load, providing a new solution for deep peak regulation of the heating unit.

[0037] 2. Thermal energy utilization model with two-way collaborative optimization: A multi-path diversion strategy for molten salt heat is proposed, which not only optimizes the heat storage and release process, but also realizes the multifunctional coordination of power generation load increase, boiler feed water heating, and heat network heating.

[0038] Third, the technical solution of the present invention solves the technical problems that people have been eager to solve but have never been able to solve: the present invention provides the following effective solutions to the technical problems faced by traditional coal-fired heating and power generation systems, such as insufficient load regulation capacity and limited peak regulation depth:

[0039] 1. Breaking through the minimum load limit of boiler operation: Through the introduction and coordinated operation of the heat storage system, the unit can flexibly increase or decrease the load without changing the boiler heat load, solving the adjustment lag problem caused by the thermal inertia of the boiler in the traditional system.

[0040] 2. Achieve comprehensive optimization of thermal-electric decoupling: For a long time, the coupling of the cogeneration system has limited its peak-shaving flexibility. The present invention not only optimizes the dynamic process of thermal-electric decoupling through the deep coupling of heat storage technology, but also greatly expands the thermal-electric load characteristic range.

[0041] 3. Improve the load increase rate: The multi-path shunt design of high-temperature molten salt improves the ability of the power generation system to quickly respond to grid demand, which is difficult to achieve in traditional solutions.

[0042] Fourth, the technical solution of the present invention overcomes technical prejudice: the present invention breaks the technical boundary between traditional heat storage system and heat power generation system in the design process, and overcomes the prejudice of the industry against the following technical limitations:

[0043] 1. The concept that "heat storage system can only provide auxiliary peak regulation": The traditional view is that the heat storage system is mainly used for peak shaving and valley filling. However, the present invention, through the coordinated design of heat storage and heat release, makes it the core means of system load regulation. It is not only used to assist boiler operation, but also directly participates in the dynamic regulation of power generation and heat supply.

[0044] 2. Limitation of “molten salt is only used for one-way heat storage or release”: The present invention innovatively proposes a multi-path diversion strategy for molten salt, so that it can meet multiple thermal energy needs at the same time, realizing two-way optimization of heat storage and release. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural diagram of a heat supply and power generation system for improving the flexibility of thermal power load by coupling molten salt heat storage provided by an embodiment of the present invention;

[0046] Figure 2 It is a flow chart of a method for operating a heating and power generation system coupled with molten salt heat storage to improve the flexibility of thermal power loads provided by an embodiment of the present invention;

[0047] Figure 3 The original thermal power load range of the 700MW subcritical coal-fired unit when not coupled with the heat storage system and the improved load range after coupling with the patented solution of the present invention are shown.

[0048] In the figure: 1. Boiler; 2. High-pressure cylinder of steam turbine; 3. Diverter valve; 4. Diverter valve; 5. Medium-pressure cylinder of steam turbine; 6. Low-pressure cylinder of steam turbine; 7. Generator; 8. Condenser; 9. Condensate pump; 10. Low-pressure heater; 11. Deaerator; 12. Feedwater pump; 13. High-pressure heater; 14. Diverter valve; 15. Mixing valve; 16. Diverter valve; 17. Mixing valve; 18. Diverter valve; 19. Mixing valve; 20. Heat storage heat exchanger; 21 , electric heater; 22. electric heater; 23. mixing valve; 24. high-temperature heat storage tank; 25. low-temperature heat storage tank; 26. diverter valve; 27. high-temperature heat release preheater; 28. high-temperature heat release evaporator; 29. ​​high-temperature heat release superheater; 30. diverter valve; 31. low-temperature heat release heat exchanger; 32. mixing valve; 33. low-temperature water outlet of heating network; 34. molten salt heat exchanger of heating network; 35. low-temperature water inlet; 36. diverter valve; 37. mixing valve. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] like Figure 1As shown, a heat supply and power generation system coupled with molten salt heat storage to improve the flexibility of thermal power load of the present invention comprises a coal-fired power generation system, a molten salt cooperative heat storage system coupled thereto, and a heating network heating system;

[0051] The coal-fired power generation system comprises a boiler 1, a steam turbine high-pressure cylinder 2, a diverter valve 3, a diverter valve 4, a steam turbine medium-pressure cylinder 5, a steam turbine low-pressure cylinder 6, a generator 7, a condenser 8, a condensate pump 9, a low-pressure heater 10, a deaerator 11, a feedwater pump 12, a high-pressure heater 13, a diverter valve 14, a mixing valve 15, a diverter valve 16, a mixing valve 17, a diverter valve 18, and a mixing valve 19; the main steam outlet of the boiler 1 is connected to the inlet of the mixing valve 17, and the outlet of the mixing valve 17 is connected to the steam inlet of the steam turbine high-pressure cylinder 2; the steam extraction outlet of the steam turbine high-pressure cylinder 2 is connected to the steam extraction inlet of the high-pressure heater 13, and the steam outlet of the steam turbine high-pressure cylinder 2 is connected to the inlet of the diverter valve 3 ; The diverter valve 3 divides the steam into two paths, one of which is connected to the inlet of the diverter valve 4, and the other is connected to the extraction steam inlet of the high-pressure heater 13; the diverter valve 4 divides the steam into two paths, one of which is connected to the reheat steam inlet of the boiler 1, and the other is connected to the steam inlet of the heat supply heat exchanger 38; the reheat steam outlet of the boiler 1 is connected to the inlet of the diverter valve 18; the diverter valve 18 divides the reheat steam into two paths, one of which enters the turbine intermediate pressure cylinder 5, and the other enters the heat storage heat exchanger 20 in the heat storage circuit of the molten salt collaborative heat storage system; the extraction steam outlet of the turbine intermediate pressure cylinder 5 is connected to the extraction steam inlets of the high-pressure heater 13 and the deaerator 11, and the steam outlet of the turbine intermediate pressure cylinder 5 is connected to the mixing valve 19; the mixing The outlet of valve 19 is connected to the steam inlet of the low-pressure cylinder 6 of the steam turbine; the extraction steam of the low-pressure cylinder 6 of the steam turbine is connected to the low-pressure heater 10, and the steam outlet of the low-pressure cylinder 6 of the steam turbine is connected to the steam inlet of the condenser 8; the condensate outlet of the condenser 8 is connected to the inlet of the condensate pump 9; the outlet of the condensate pump 9 is connected to the water working medium inlet of the low-pressure heater 10; the water working medium outlet of the low-pressure heater 10 is connected to the water working medium inlet of the deaerator 11, and the drain outlet of the low-pressure heater 10 is connected to the drain inlet of the condenser 8; the water working medium outlet of the deaerator 11 is connected to the inlet of the feed water pump 12; the outlet of the feed water pump 12 is connected to the water working medium inlet of the high-pressure heater 13; The water working medium outlet is connected to the diverter valve 14, and the drain outlet of the high-pressure heater 13 is connected to the drain inlet of the deaerator 11; the diverter valve 14 divides the water working medium into two parts, one part enters the water working medium inlet of the low-temperature heat exchanger 20 of the heat release loop of the molten salt storage and cooperative heat storage system, and the other part enters the water supply inlet of the water supply mixing valve 15; the outlet of the water supply mixing valve 15 is connected to the diverter valve 16; the diverter valve 16 divides the water working medium into two parts, one part enters the water working medium inlet of the high-temperature preheater 26, and the other part enters the water supply inlet of the boiler 1; the turbine high-pressure cylinder 2, the turbine intermediate-pressure cylinder 5 and the turbine low-pressure cylinder 6 are connected through a rotating shaft, and jointly drive the generator 7 to output electrical power to the outside;

[0052] The heat storage circuit of the molten salt collaborative heat storage system includes a high-temperature heat storage tank 24, a low-temperature heat storage tank 25, a heat storage heat exchanger 20, an electric heater 21, an electric heater 22, a mixing valve 23, and a diverter valve 26; the outlet of the low-temperature heat storage tank 25 is connected to the inlet of the diverter valve 26; the diverter valve 26 divides the low-temperature molten salt into two paths, one leading to the molten salt inlet of the heat storage heat exchanger 20, and the other leading to the molten salt inlet of the electric heater 22; the molten salt outlet of the heat storage heat exchanger 20 is connected to the inlet of the electric heater 21, and the steam outlet of the heat storage heat exchanger 20 is connected to the steam inlet of the mixing valve 19; the molten salt outlet of the electric heater 22 is connected to the inlet of the mixing valve 23; the molten salt outlet of the electric heater 21 is connected to the inlet of the mixing valve 23; the outlet of the mixing valve 23 is connected to the inlet of the high-temperature heat storage tank 24;

[0053] The heat release circuit of the molten salt collaborative heat storage system includes a high-temperature heat storage tank 24, a low-temperature heat storage tank 25, a diverter valve 14, a low-temperature heat release heat exchanger 31, a mixing valve 20, a diverter valve 16, a high-temperature heat release preheater 27, a high-temperature heat release evaporator 28, a high-temperature heat release superheater 29, a diverter valve 30, a mixing valve 32, a diverter valve 36, and a mixing valve 37; the molten salt outlet of the high-temperature heat storage tank 24 is connected to the inlet of the diverter valve 30, and the diverter valve 30 divides the molten salt into three paths, one leading to the inlet of the mixing valve 32, one leading to the molten salt inlet of the high-temperature heat release superheater 29, and one leading to the molten salt inlet of the low-temperature heat release heat exchanger 31; the molten salt outlet of the high-temperature heat release superheater 29 is connected to the molten salt inlet of the high-temperature heat release evaporator 28, the steam inlet of the high-temperature heat release superheater 29 is connected to the steam outlet vector of the high-temperature heat release evaporator 28, and the steam outlet of the high-temperature heat release superheater 29 is connected to the mixing valve 17; The molten salt outlet of the heat-releasing evaporator 28 is connected to the molten salt inlet of the high-temperature heat-releasing preheater 27, and the steam inlet of the high-temperature heat-releasing evaporator 28 is connected to the steam outlet of the high-temperature heat-releasing preheater 27; the molten salt outlet of the high-temperature heat-releasing preheater 27 is connected to the inlet of the mixing valve 32, and the water working medium inlet of the high-temperature heat-releasing preheater 27 is connected to the water supply working medium outlet of the diverter valve 16; the molten salt outlet of the low-temperature heat-releasing heat exchanger 31 is connected to the inlet of the mixing valve 32, the water working medium inlet of the low-temperature heat-releasing heat exchanger 31 is connected to the water supply outlet of the diverter valve 14, and the water working medium outlet of the low-temperature heat-releasing heat exchanger 31 is connected to the inlet of the mixing valve 15; the outlet of the mixing valve 32 is connected to the inlet of the diverter valve 36; the diverter valve 36 divides the molten salt into two paths, one leading to the molten salt inlet of the molten salt heat exchanger 34 of the heating network, and the other leading to the inlet of the mixer 37; the molten salt outlet of the mixer 37 is connected to the inlet of the low-temperature heat storage tank 25;

[0054] The molten salt heating heating network circuit of the heating network heating system includes a heating network low-temperature water inlet 35, a heating network low-temperature water outlet 33, and a heating network molten salt heat exchanger 34; the molten salt inlet of the heating network molten salt heat exchanger 34 is connected to the outlet of the diverter valve 36, the molten salt outlet of the heating network molten salt heat exchanger 34 is connected to the inlet of the mixing valve 37, and the hot water inlet of the heating network molten salt heat exchanger 34 is connected to the low-temperature water inlet 35;

[0055] The steam heating network circuit of the heating system of the heating network includes a heating network low-temperature water inlet 38, a heating network low-temperature water outlet 40, and a heating network steam heat exchanger 39; the hot water outlet of the heating network molten salt heat exchanger 34 is connected to the low-temperature water outlet 33; the steam inlet of the heating network steam heat exchanger 39 is connected to the outlet of the diverter valve 4, the steam outlet of the heating network steam heat exchanger 38 is connected to the condenser 8, the hot water inlet of the heating network steam heat exchanger 39 is connected to the low-temperature water inlet 38, and the hot water outlet of the heating network steam heat exchanger 39 is connected to the low-temperature water outlet 40.

[0056] The coal-fired power generation system is the core of the heating and power generation system. The boiler 1 generates high-temperature and high-pressure steam. The steam enters the high-pressure cylinder 2, the medium-pressure cylinder 5 and the low-pressure cylinder 6 of the steam turbine to expand in sequence and drive the generator 7 to generate electricity. The main steam of the boiler enters the high-pressure cylinder of the steam turbine through the mixing valve 17. The steam extraction of the high-pressure cylinder of the steam turbine is used to heat the high-pressure heater 13. At the same time, part of the steam outlet enters the medium-pressure cylinder to complete the expansion. The steam extraction of the medium-pressure cylinder further heats the deaerator 11. The steam outlet of the low-pressure cylinder is connected to the condenser 8. After the steam is condensed into water, it is heated by the condensate pump 9 and the heater and then sent back to the boiler to complete the cycle.

[0057] The heat storage circuit achieves heat storage of molten salt through high-temperature heat storage tank 24 and low-temperature heat storage tank 25. The reheated steam from the boiler partially enters the heat storage heat exchanger 20 through the diverter valve 18, heats the low-temperature molten salt and stores it in the high-temperature heat storage tank 24. The heating of the molten salt can also be achieved through electric heaters 21 and 22 to utilize off-peak power resources. The steam outlet in the heat storage heat exchanger is connected to the mixing valve 19, and the steam that is not used for heat storage can directly enter the intermediate pressure cylinder of the steam turbine to complete the conventional power generation function.

[0058] The heat release circuit draws out molten salt from the high-temperature heat storage tank 24, and introduces the molten salt into the high-temperature heat release superheater 29, the high-temperature heat release evaporator 28, the high-temperature heat release preheater 27 and the low-temperature heat release heat exchanger 31 through the diverter valve 30, and uses the heat of the molten salt to heat the water working medium and generate steam. The generated high-temperature steam is sent to the high-pressure cylinder of the steam turbine through the mixing valve 17 to improve the power generation efficiency. At the same time, the low-temperature molten salt is collected into the low-temperature heat storage tank 25 through the mixing valve 32 to complete the heat release cycle.

[0059] The molten salt is divided into two paths through the diverter valve 36. One path enters the molten salt heat exchanger 34 of the heating network to heat the low-temperature water of the heating network, raise its temperature and transport it to the heat user. The molten salt after heat exchange returns to the low-temperature heat storage tank 25 through the mixer 37 to complete the closed-loop circulation of the molten salt. In this way, the system can flexibly adjust the heat-to-electricity ratio in different seasons to meet the heating demand.

[0060] The steam heating network loop guides part of the steam into the heating network steam heat exchanger 39 through the diverter valve 4 to provide heat for the low-temperature water. The condensed steam after heat exchange returns to the condenser 8 through the outlet, thereby maintaining the closed-loop operation of the steam. This process is mainly used to meet the high-efficiency heating demand during winter when the heating demand is high.

[0061] This system achieves flexible switching between power generation and heat supply through dynamic adjustment of the diverter valve and the mixing valve. Through the molten salt collaborative heat storage system, the system can store heat during low power load periods and release heat during peak periods, thereby improving the flexibility and comprehensive energy efficiency of the unit. Experimental data show that the system not only achieves thermal and electrical decoupling, but also effectively improves overall efficiency, reduces heating costs and grid pressure.

[0062] In summary, the heating and power generation system utilizes the high heat capacity characteristics of molten salt, combines coal-fired power generation and heating networks, and achieves a high degree of integration of heat storage, heat release, power generation and heat supply, meeting the needs of industrial and civil heating, while improving the operating economy and flexibility of the power plant.

[0063] As a preferred embodiment of the present invention, the electric energy source of the electric heater 21 and the electric heater 22 is the electricity that cannot be accessed to the grid during the deep peak regulation period of the coal-fired power generation system. The advantage is that it can effectively reduce the electric load rate of the coupled heating and power generation system, and even achieve zero electric power output, effectively expanding the electric load width of the coupled heating and power generation system.

[0064] Furthermore, the high-temperature heat storage tank 24 is filled with high-temperature molten salt, and the low-temperature heat storage tank 25 is filled with low-temperature molten salt. The advantage is that when the coupled heating and power generation system reduces the power supply load, the low-temperature molten salt is heated to high-temperature molten salt by the heat of the reheated steam for storage, and the excess electric energy is stored in the form of heat energy by electric heating, which can effectively reduce the minimum electric load rate of the coupled heating and power generation system, expand the peak-down depth of the coupled heating and power generation system, and achieve zero electric power output of the power generation system under the condition that the boiler maintains the minimum operating load, thereby improving its load change rate. When the coupled heating and power generation system increases the power supply load, while keeping the boiler heat load unchanged, the high-temperature molten salt is divided into three parts by a diverter valve, one part is used to increase the boiler feed water temperature, one part is used to produce the amount of superheated steam required to increase the power generation load, and the remaining part of the high-temperature molten salt is used to heat the heat network, thereby improving the load increase rate and heating load of the coupled heating and power generation system. By coupling an innovative heat storage system with a synergistic heat storage and synergistic heat release structure, the range of thermal and electric load characteristics of the coupled heating and power generation system is significantly expanded, the load variation rate of the coupled heating and power generation system is improved, and the flexibility of its heating and power supply is enhanced.

[0065] The coal-fired power generation system converts coal into high-temperature and high-pressure steam through boiler 1. The steam passes through the high-pressure cylinder 2, medium-pressure cylinder 5, and low-pressure cylinder 6 of the steam turbine in turn, driving the generator 7 to output electrical energy. After the steam completes the work energy, it is condensed into water through the condenser 8, and then passes through the condensate pump 9, low-pressure heater 10, deaerator 11 and feed water pump 12 to heat the water working medium and send it back to the boiler 1 to complete the cycle. Under normal operating conditions, the system adjusts the diverter valve 3, diverter valve 4 and other key valves according to the load demand to ensure power generation efficiency and system stability.

[0066] When the grid load is low or the coal-fired power generation system needs to reduce the power load to participate in downward peak regulation, the system opens the heat storage circuit of the molten salt collaborative heat storage system. The low-temperature molten salt flows from the low-temperature heat storage tank 25 into the diverter valve 26, and a part of it enters the heat storage heat exchanger 20, absorbs the heat from the reheated steam of the coal-fired power generation system, and enters the high-temperature heat storage tank 24 for storage after heating; the other part of the low-temperature molten salt flows through the electric heater 21 and the electric heater 22, and is heated to a high temperature by the excess electric energy of the coal-fired power generation system before being stored. This process can effectively utilize the electric energy that cannot be connected to the Internet and improve energy efficiency.

[0067] When the grid load is high or the system needs to participate in upward deep peak regulation, the heat release circuit of the molten salt cooperative heat storage system is turned on. The high-temperature molten salt flows out from the high-temperature heat storage tank 24, and after being regulated by the diverter valve 30, enters the high-temperature heat release preheater 27, high-temperature heat release evaporator 28, high-temperature heat release superheater 29 and other equipment, transfers heat to the feed water working fluid and generates high-quality superheated steam, which is sent to the turbine intermediate pressure cylinder 5 or the mixing valve 17 to improve the power supply capacity of the system.

[0068] When regional heating is required, the system transfers heat to the heating network through the heating network heating system. In the molten salt heating network loop, the high-temperature molten salt passes through the heating network molten salt heat exchanger 34 to heat the low-temperature hot water, and completes the heating cycle through the heating network low-temperature water inlet 35 and low-temperature water outlet 33; in the steam heating network loop, the reheated steam of the coal-fired power generation system passes through the heating network steam heat exchanger 39 to quickly heat the low-temperature hot water to meet the regional heating needs.

[0069] The system uses control elements such as diverter valve 14 and diverter valve 18 to flexibly adjust the distribution ratio of reheat steam to meet the different needs of power generation and heat supply. When the grid load demand is high, the power generation load is increased by increasing the feed water flow or increasing the heat release of molten salt; when the grid load demand is low, the excess heat is stored in the heat storage circuit to reduce the power output and realize flexible peak regulation of the system.

[0070] Through the molten salt heat storage and release system, the system can achieve efficient conversion and storage of thermal energy and electrical energy, and flexibly switch between power generation and heat supply. The molten salt heat storage system optimizes the operating parameters of the heat exchanger and valves, maintains the stability of the molten salt flow and temperature during the heat storage and release process, reduces heat loss, improves the operating efficiency of the entire system, and ensures reliability and economy under multiple working conditions.

[0071] like Figure 2 As shown, an operation method for coupling molten salt thermal storage to improve the flexibility of thermal power load is as follows:

[0072] S1: When the electric load rate of the coupled heating and power generation system needs to remain unchanged, or its own variable load capacity can meet the load change requirements, and there is no need to store or release heat, and there is no need to provide heat for the heating system of the heating network, the coal-fired power generation system maintains its operating state and increases or decreases the water flow rate according to the load change requirements; the molten salt collaborative heat storage system does not store or release heat; the heating system of the heating network does not provide heat;

[0073] S2: When the electric load rate of the coupled heating and power generation system needs to remain unchanged, or its own variable load capacity can meet the load change requirements, and it is necessary to provide heat for the heating system of the heating network, the molten salt heating network loop is opened, the coal-fired power generation system maintains its operating state, and increases or decreases the water supply flow rate according to the load change requirements; the molten salt collaborative heat storage system does not store or release heat; in the heating system of the heating network, the molten salt at the outlet of the diverter valve 36 is adjusted to flow into the molten salt inlet of the molten salt heat exchanger 34 of the heating network, and the opening of the diverter valve 30 is adjusted to provide the molten salt mass flow required by the molten salt heat exchanger 34 of the heating network;

[0074] S3: When the coupled heating and power generation system needs to increase the power supply load, participate in the upward deep peak regulation, and does not need to provide heat for the heating system of the heating network, the heat release circuit of the heat storage system is opened. In the coal-fired power generation system, the feed water temperature is increased by adjusting the opening of the diverter valve 14, and the opening of the diverter valve 16 is adjusted to heat part of the heated feed water to superheated steam through the high-temperature heat release preheater 27, the high-temperature heat release evaporator 28, and the high-temperature heat release superheater 29. At the same time, the feed water flow rate is increased to increase the electric load rate of the coupled heating and power generation system, so as to realize the improvement of the upward peak regulation depth of the coupled heating and power generation system; in the heat storage system, the molten salt at the outlet of the diverter valve 36 is adjusted to flow into the mixing valve 37, and the feed water temperature at the outlet of the mixing valve 15 is adjusted by adjusting the opening of the diverter valve 30, and the working temperature requirements of the high-temperature heat release preheater 27, the high-temperature heat release evaporator 28, and the high-temperature heat release superheater 29 are met; the heating system of the heating network does not provide heat;

[0075] S4: On this basis, when the heating system of the heating network changes its state and needs to be coupled to the heating power generation system to provide heat for it, the molten salt heat collection network loop is opened, and the molten salt at the outlet of the diverter valve 36 is adjusted to flow into the molten salt inlet of the molten salt heat exchanger 34 of the heating network, and the opening of the diverter valve 30 is adjusted to provide the molten salt mass flow required by the molten salt heat exchanger 34 of the heating network;

[0076] S5: When the coupled heating and power generation system needs to reduce the power supply load and participate in the downward deep peak regulation, and does not need to provide heat for the heating system of the heating network, the heat storage loop of the heat storage system is turned on. In the coal-fired power generation system, the electric load rate of the coupled heating and power generation system is reduced by adjusting the opening of the diverter valve 18; in the heat storage system, the electric load rate of the coupled heating and power generation system is reduced by adjusting the electric heating power of the electric heater 22, so as to improve the downward peak regulation depth of the coupled heating and power generation system; the heating system of the heating network does not provide heat;

[0077] S6: On this basis, when the heating network heating system changes its state and needs to be coupled with the heating and power generation system to provide heat for it, the steam heating network circuit of the heating network heating system is opened, and the heating amount is adjusted by adjusting the opening of the diverter valve 4, while reducing the electrical load rate of the coupled heating and power generation system.

[0078] As a preferred embodiment of the present invention, the temperature of the low temperature tank is 295°C, and the temperature of the high temperature tank is 560°C.

[0079] As a preferred embodiment of the present invention, the outlet molten salt temperature of the electric heater 21 and the electric heater 22 is 560°C.

[0080] As a preferred embodiment of the present invention, in the heating network heating system, the mass flow rate of molten salt flowing through the heating network molten salt heat exchanger 34 is determined by the required mass flow rate of the heating network low-temperature water inlet 35, and the mass flow rate of steam flowing through the heating network steam heat exchanger 39 is determined by the required mass flow rate of the heating network low-temperature water inlet 38.

[0081] As a preferred embodiment of the present invention, the total reheat steam flow rate diverted by the diverter valve 4 and the diverter valve 18 is limited by the minimum flow rate of the turbine intermediate pressure cylinder 2 and should not exceed 79% of the total reheat steam flow rate.

[0082] As a preferred embodiment of the present invention, in the heat storage circuit of the molten salt collaborative heat storage system, the opening of the valve 26 is determined by the mass flow rate flowing through the heat storage heat exchanger 20 and the electric heating power of the electric heater 22.

[0083] As a preferred embodiment of the present invention, the steam outlet temperature of the heat storage heat exchanger 20 should be kept the same as the steam outlet temperature of the intermediate pressure cylinder 5 of the steam turbine, and the temperature range is 339°C to 354°C.

[0084] As a preferred embodiment of the present invention, in the heat release circuit of the molten salt collaborative heat storage system, the opening degree of the valve 30 is determined by the mass flow rate flowing through the low-temperature heat release heat exchanger 31 and the high-temperature heat release superheater 29 .

[0085] As a preferred embodiment of the present invention, the maximum opening degree of the diverter valve 14 is 35%.

[0086] As a preferred embodiment of the present invention, the temperature range of the steam at the outlet of the low-temperature heat release heat exchanger 31 is 224°C to 345°C.

[0087] In order to more intuitively illustrate the innovation and technical value of the technical solution of the present invention, a specific thermal power load interval comparison diagram is provided (see Figure 3 ).

[0088] exist Figure 3 In the figure, the original thermal load range of the 700MW subcritical coal-fired unit without the thermal storage system and the improved load range after coupling the patented solution of the present invention are shown. It can be seen that after adopting the patented solution of the present invention, the thermal load boundary of the system has been significantly expanded.

[0089] When the thermal load is at its maximum value, the upper limit of the electrical load is increased from the original 338MW to 744MW.

[0090] When the thermal load is maintained at the minimum value, the lower limit of the electrical load is reduced from the original 121MW to 0MW, achieving zero electrical power output.

[0091] Figure 3The advantages of the technical solution of the present invention in terms of load regulation flexibility are clearly explained: by coordinating the heat storage and release processes, the system can greatly adapt to the peak-shaving needs of the power system and the heating needs of the heat network while maintaining the stability of the boiler heat load.

[0092] This breakthrough performance improvement significantly overcomes the technical bottleneck of limited load regulation range of existing coal-fired units and provides an innovative solution for the flexibility transformation of coal-fired units.

[0093] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0094] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A heating and power generation system coupled with molten salt heat storage to improve the flexibility of thermal power load, characterized in that: The system includes a coal-fired power generation system, a molten salt coordinated heat storage system coupled thereto, and a heating network heating system; The coal-fired power generation system comprises: Boiler (1), steam turbine high pressure cylinder (2), steam turbine intermediate pressure cylinder (5), steam turbine low pressure cylinder (6), generator (7), condenser (8), and associated feed water pump (12), heater and valve; The coal-fired power generation system is coupled with the molten salt cooperative heat storage system, and a heat storage heat exchanger (20) is used to divert part of the reheated steam to the molten salt heat storage loop, and the molten salt is heated or released through an electric heater (21), an electric heater (22) or a heating network molten salt heat exchanger (34), thereby forming a circulation flow of high and low temperature molten salt; The molten salt collaborative heat storage system comprises: A high-temperature heat storage tank (24) and a low-temperature heat storage tank (25) are used to store high-temperature and low-temperature molten salts; The heat storage circuit and the heat release circuit respectively complete heat storage and release through the heat storage heat exchanger (20), the electric heater (21), the high-temperature heat release preheater (27), and the low-temperature heat release heat exchanger (31); The heating network heating system comprises: The heating network molten salt heat exchanger (34) and the heating network steam heat exchanger (39) heat the low-temperature water of the heating network through molten salt and steam respectively, so as to meet the regional heating demand.

2. The heating and power generation system for improving thermal power load flexibility by coupling molten salt heat storage according to claim 1 is characterized in that: The electric energy source of the electric heater (21) and the electric heater (22) is the electricity that is generated by the coal-fired power generation system during the deep peak regulation period and cannot be connected to the grid, so as to improve the utilization rate of electricity.

3. The heating and power generation system for improving thermal power load flexibility by coupling molten salt heat storage according to claim 1 is characterized in that: The high-temperature heat storage tank (24) contains high-temperature molten salt, and the low-temperature heat storage tank (25) contains low-temperature molten salt. The molten salt realizes efficient recycling of heat through heat storage and heat release loops.

4. The heating and power generation system for improving thermal power load flexibility by coupling molten salt heat storage according to claim 1 is characterized in that: The diverter valve (26) in the heat storage circuit divides the low-temperature molten salt into two paths, one leading to the heat storage heat exchanger (20) and the other leading to the electric heater (22), so as to achieve flexible distribution and efficient energy storage of the molten salt during the heat storage process.

5. The heating and power generation system for improving thermal power load flexibility by coupling molten salt heat storage according to claim 1 is characterized in that: The diverter valve (30) in the heat release circuit divides the high-temperature molten salt into three paths, which enter the high-temperature heat release superheater (29), the low-temperature heat release heat exchanger (31) and the mixing valve (32) respectively, so as to meet the thermal energy requirements under different working conditions of heat supply and power generation.

6. The heating and power generation system for improving thermal power load flexibility by coupling molten salt heat storage according to claim 1 is characterized in that: The heating network heating system comprises a molten salt heating network loop and a steam heating network loop. The molten salt heating network loop heats low-temperature hot water via a heating network molten salt heat exchanger (34), and the steam heating network loop provides rapid heating service for low-temperature hot water via a heating network steam heat exchanger (39).

7. An operating method for improving the flexibility of thermal power load by coupling molten salt heat storage in a thermal power generation system for improving the flexibility of thermal power load by coupling molten salt heat storage as claimed in any one of claims 1 to 6, characterized in that: The method is as follows: 1) The coal-fired power generation system adjusts its operating state according to the power load demand, and the molten salt cooperative heat storage system switches between the heat storage loop or the heat release loop; 2) In the deep peak-shaving mode, the coal-fired power generation system adjusts the reheat steam flow to the steam turbine or the heat storage circuit through the diverter valve to achieve upward or downward peak-shaving; 3) In the heating demand mode, the molten salt cooperative heat storage system provides heat for low-temperature water through the molten salt heat exchanger or steam heat exchanger of the heating network heating system; 4) adjusting the opening of the diverter valve (36) and the diverter valve (30) to control the flow rate of the molten salt to meet the operation requirements of the heat storage, heat release and heat supply systems.

8. The method according to claim 7, characterized in that When the coupled heating and power generation system needs to reduce the electric load to participate in the downward deep peak regulation, the heat storage circuit of the heat storage system is opened, and the electric load rate in the molten salt heat storage process is reduced by adjusting the electric heating power of the electric heater (22), and at the same time, the diverter valve (18) is adjusted to reduce the reheat steam flow.

9. The method according to claim 7, characterized in that: When the heating system of the heating network needs to meet the regional heating demand, the molten salt collaborative heat storage system adjusts the molten salt flow to the molten salt heat exchanger (34) of the heating network through the diverter valve (36), and calculates the required molten salt mass flow based on the mass flow of the low-temperature water inlet (35), providing accurate heating capacity.

10. The method according to claim 7, characterized in that When the heat release circuit of the heat storage system is in operation, the opening of the diverter valve (30) is adjusted to control the flow rate of the molten salt flowing through the low-temperature heat release heat exchanger (31) and the high-temperature heat release superheater (29), and the temperature of the molten salt is adjusted through the mixing valve (32) to meet the operating requirements of the high-temperature heat release component. The steam outlet temperature during the heat release process is maintained in the range of 339°C to 354°C.

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