Solid and molten salt thermal energy storage system for cogen peak shaving and method thereof

Abstract

The present application relates to a kind of solid and molten salt heat storage system and its method for combined heat and power peak shaving, including steam turbine unit, high-temperature solid heat storage subsystem, low-temperature molten salt heat storage subsystem and water supply subsystem, high-temperature solid heat storage subsystem includes high-temperature solid heat accumulator, high-temperature fan and steam superheater, low-temperature molten salt heat storage subsystem includes low-temperature molten salt hot tank, molten salt heat-releasing steam generator, molten salt heat-releasing water supply heater, low-temperature molten salt cold tank and low-temperature molten salt heating assembly, water outlet of water supply subsystem, molten salt heat-releasing water supply heater, molten salt heat-releasing steam generator, steam superheater and steam turbine unit steam inlet are sequentially communicated to constitute steam supply circuit;Low-temperature molten salt heating assembly steam inlet and steam turbine unit reheat steam outlet are communicated for heating low-temperature molten salt;This system is by series connection setting low-temperature molten salt heat storage subsystem and high-temperature solid heat storage subsystem, realize wide temperature range heat storage and high-temperature high-quality heat energy utilization, solve the problem of traditional heat storage system operation temperature zone is narrower.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cogeneration peak shaving, in particular to a solid and molten salt heat storage system for cogeneration peak shaving and a method thereof. BACKGROUND

[0002] To ensure the energy supply safety of the new power system, it is necessary to further develop the thermal-electric decoupling technology and strengthen the peak shaving and top peak shaving capacity of the cogeneration unit. Adding an energy storage link to the cogeneration unit can improve the thermal inertia of the unit operation, further optimize the thermal-electric decoupling operation capacity of the unit, solve the limitations caused by the mismatch between the time, space or intensity of the heat supply and demand, and maximize the energy utilization rate of the cogeneration system.

[0003] Currently, the industry mostly uses a heat storage water tank or a heat storage electric boiler as an energy storage link to realize heat storage and release, but the above-mentioned devices use low-pressure water as the energy storage medium, and the storage temperature is relatively low. Therefore, they cannot realize the storage and utilization of high-grade energy, and the application scenarios of energy storage are also affected by the temperature of the medium, and they can only be applied to low-temperature steam and domestic heating. To further strengthen the heat storage capacity of the energy storage link of the cogeneration unit and expand the heat release application scenarios of the energy storage link, the present application is invented.

[0004] The present application combines the molten salt heat storage technology and the high-temperature solid heat storage technology to realize the storage, release and utilization of high-grade heat energy. The molten salt heat storage technology is a technology that has gradually developed in recent years. The molten salt heat storage technology has the advantages of large energy storage capacity, long storage period and low cost, and is more suitable for large-scale energy storage demand than other energy storage technologies. Under the current double carbon target of "3060", the molten salt heat storage technology is used for the flexible peak shaving modification of cogeneration, to improve the operation capacity of the unit for deep peak shaving and top peak shaving. However, due to the relatively narrow working temperature range of the molten salt, the single use of the molten salt medium to establish a heat storage system cannot realize temperature matching with the steam generated by the cogeneration unit, and cannot realize the cascade utilization of energy, resulting in energy waste and quality degradation. Therefore, it is necessary to expand the operating temperature range of the molten salt heat storage system and improve the overall energy supply capacity and heat release efficiency of the system.

[0005] The introduction of the high-temperature solid heat storage technology into the heat storage system can directly use electric energy to heat the solid heat storage medium, expand the operating temperature range of the heat storage system, realize the storage of high-temperature and high-quality heat energy, and ensure the stable and energy-efficient operation of the heat storage system. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the defect that the narrow operating temperature range of the molten salt heat storage system in the prior art cannot realize temperature matching with the steam generated by the cogeneration unit, resulting in energy waste and quality degradation, so as to provide a solid and molten salt heat storage system for cogeneration peak shaving and a method thereof.

[0007] To achieve the above object, the present application adopts the following technical solutions:

[0008] A solid and molten salt heat storage system for combined heat and power peak shaving, comprising a steam turbine unit, a high-temperature solid heat storage subsystem, a low-temperature molten salt heat storage subsystem and a water supply subsystem, wherein a steam inlet of the steam turbine unit is communicated with a steam outlet pipe of a boiler;

[0009] The high-temperature solid heat storage subsystem comprises a high-temperature solid heat storage device, a high-temperature fan and a steam superheater, the high-temperature solid heat storage device is heated by electricity, an air outlet of the high-temperature solid heat storage device is communicated with an air inlet of the high-temperature fan, an air outlet of the high-temperature fan is communicated with an air inlet of the steam superheater, and an air outlet of the steam superheater is communicated with an air inlet of the high-temperature solid heat storage device;

[0010] The low-temperature molten salt heat storage subsystem comprises a low-temperature molten salt hot tank, a molten salt heat-releasing steam generator, a molten salt heat-releasing water supply heater, a low-temperature molten salt cold tank and a low-temperature molten salt heating assembly, a molten salt outlet of the low-temperature molten salt hot tank is provided with a molten salt high-temperature circulating pump, a molten salt outlet of the molten salt high-temperature circulating pump is communicated with a molten salt inlet of the molten salt heat-releasing steam generator, a molten salt outlet of the molten salt heat-releasing steam generator is communicated with a molten salt inlet of the molten salt heat-releasing water supply heater, a molten salt outlet of the molten salt heat-releasing water supply heater is communicated with a molten salt inlet of the low-temperature molten salt cold tank, a molten salt outlet of the low-temperature molten salt cold tank is communicated with a molten salt inlet of the low-temperature molten salt heating assembly, a molten salt inlet of the low-temperature molten salt heating assembly is provided with a molten salt low-temperature circulating pump, and a molten salt outlet of the low-temperature molten salt heating assembly is connected with a molten salt inlet of the low-temperature molten salt hot tank;

[0011] A water outlet of the water supply subsystem, the molten salt heat-releasing water supply heater, the molten salt heat-releasing steam generator, the steam superheater and the steam inlet of the steam turbine unit are sequentially communicated to form a steam supply loop;

[0012] A steam inlet of the low-temperature molten salt heating assembly and a reheated steam outlet of the steam turbine unit are communicated to heat the low-temperature molten salt.

[0013] Preferably, the low-temperature molten salt heating assembly comprises a low-temperature molten salt electric heater and a low-temperature molten salt steam heater, a molten salt inlet of the low-temperature molten salt electric heater is communicated with a molten salt outlet of the molten salt low-temperature circulating pump, a molten salt outlet of the low-temperature molten salt electric heater is communicated with a molten salt inlet of the low-temperature molten salt steam heater, and a molten salt outlet of the low-temperature molten salt steam heater is communicated with a molten salt inlet of the low-temperature molten salt hot tank; a first bypass is communicated between the molten salt inlet and the molten salt outlet of the low-temperature molten salt electric heater, and a second bypass is communicated between the molten salt inlet and the molten salt outlet of the low-temperature molten salt steam heater.

[0014] Preferably, the water supplement subsystem comprises a main water supplement pipe and a water supplement pump, the water supplement pump is connected to the water supplement pipe, and the outlet of the water supplement pump is connected to the inlet of the molten salt heat-releasing water heating device.

[0015] Preferably, the water supplement subsystem further comprises a secondary water supplement pipe, the inlet of the secondary water supplement pipe is connected to the outlet of the low-temperature molten salt heating assembly, the inlet of the secondary water supplement pipe is connected to the main water supplement pipe and is located at the inlet of the water supplement pump.

[0016] Preferably, an industrial steam pipe is connected to the steam pipeline between the inlet of the steam superheater and the outlet of the molten salt heat-releasing steam generator, and the industrial steam pipe provides steam for industrial steam users.

[0017] Preferably, the steam turbine unit comprises a steam turbine high-pressure cylinder, a steam reheater and a steam turbine low-pressure cylinder, the outlet of the boiler is connected to the inlet of the steam turbine high-pressure cylinder, the outlet of the steam turbine high-pressure cylinder is connected to the inlet of the steam reheater, the outlet of the steam reheater is connected to the inlet of the steam turbine low-pressure cylinder, and the outlet of the steam turbine low-pressure cylinder is connected to the condenser; the outlet of the steam superheater is connected to the inlet of the steam turbine high-pressure cylinder, and the reheated steam outlet of the steam reheater is connected to the steam inlet of the low-temperature molten salt heating assembly.

[0018] A method for a solid and molten salt heat storage system for combined heat and power peak shaving, comprising the following steps:

[0019] When the actual power generation is greater than the grid dispatch power generation, the system enters the heat storage mode, the low-temperature molten salt heat storage subsystem stores heat by using the steam or electricity of the boiler, and the high-temperature solid heat storage subsystem stores heat by using electricity.

[0020] When the actual power generation is less than the grid dispatch power generation, the system enters the heat release mode, the water supplement subsystem supplements water, the low-temperature molten salt heat storage subsystem and the high-temperature solid heat storage subsystem release heat at the same time, and the water is heated into high-temperature steam to supply the steam turbine unit for power generation.

[0021] Preferably, when the actual power generation is greater than the grid dispatch power generation, the system enters the heat storage mode, the low-temperature molten salt circulating pump is started, the molten salt in the low-temperature molten salt cold tank is heated by the low-temperature molten salt heating assembly by using electricity or boiler steam and then is stored in the low-temperature molten salt hot tank, and the high-temperature solid heat storage subsystem stores heat by using electricity.

[0022] Preferably, when the system participates in power peak shaving, when the actual power generation is greater than the grid dispatch power generation, the low-temperature molten salt cold tank in the above-mentioned system is heated by the boiler steam through the low-temperature molten salt heating assembly when the boiler maintains a high heat power level operation, the steam quantity is sufficient, and the unit operation is safe, allowing the reheated steam extraction quantity to be increased; when the high-level operation cost of the boiler is higher than the purchase of real-time valley electricity price, the boiler evaporation quantity is reduced for deep peak shaving, and the low-temperature molten salt in the above-mentioned low-temperature molten salt cold tank is heated by the low-temperature molten salt heating assembly using the purchased valley electricity quantity for heat storage.

[0023] When the high-level operation of the boiler corresponds to the degree of electric cost higher than the purchase of real-time valley electricity price, the boiler evaporation quantity is reduced for deep peak shaving, and the high-temperature solid heat storage subsystem uses the purchased valley electricity quantity for heat storage, otherwise the steam turbine unit itself generates electricity for heat storage.

[0024] Preferably, when the system participates in power peak shaving, when the actual power generation is less than the grid dispatch power generation, the heat release condition is entered, the high-temperature molten salt circulating pump in the above-mentioned system is started, the high-temperature molten salt in the above-mentioned low-temperature molten salt hot tank enters the above-mentioned molten salt heat-releasing steam generator and the above-mentioned molten salt heat-releasing water supply heater in sequence to exchange heat with water, and then enters the above-mentioned low-temperature molten salt cold tank; the high-temperature fan is started to drive the gas to cool the high-temperature solid heat storage medium in the above-mentioned high-temperature solid heat accumulator, and the heat is brought into the above-mentioned steam superheater; at the same time, the water supply in the above-mentioned water supply subsystem enters the above-mentioned steam turbine unit to generate electricity after being heated by the superheated steam formed by the above-mentioned molten salt heat-releasing steam generator, the above-mentioned molten salt heat-releasing water supply heater and the above-mentioned steam superheater in sequence.

[0025] Compared with the prior art, the beneficial effects of the present application are as follows:

[0026] By series connection of the low-temperature molten salt heat storage subsystem and the high-temperature solid heat storage subsystem, low-melting-point, low-decomposition-temperature molten salt and high-temperature solid are respectively applied as heat storage medium to realize wide-temperature-range heat storage and high-temperature high-quality heat energy utilization, realize cross-time-and-space cascade utilization of heat storage heat energy, solve the problem of narrow operation temperature range of the traditional heat storage system, and the system uses molten salt heat storage and solid heat storage technology to realize heat storage and heat release functions, has the advantages of fast heat storage and heat release climbing speed, simple system structure without redundancy, high reliability, large heat storage and heat release capacity, wide operation temperature range, etc., and helps the combined heat and power unit to realize wide-temperature-range flexible operation and improve the heat and electricity decoupling performance. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are only some of the embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative work based on these drawings also belong to the protection scope of the present application.

[0028] Figure 1 System block diagram of the embodiment of the present application.

[0029] Legend of reference signs:

[0030] 1, steam turbine unit; 101, high-pressure cylinder of steam turbine; 102, steam reheater; 103, low-pressure cylinder of steam turbine; 2, high-temperature solid heat storage subsystem; 21, high-temperature solid heat storage device; 22, high-temperature air blower; 23, steam superheater; 3, low-temperature molten salt heat storage subsystem; 31, low-temperature molten salt hot tank; 32, molten salt high-temperature circulating pump; 33, molten salt heat-releasing steam generator; 34, molten salt heat-releasing water supply heater; 35, low-temperature molten salt cold tank; 36, molten salt low-temperature circulating pump; 37, low-temperature molten salt electric heater; 38, low-temperature molten salt steam heater; 4, water supply subsystem; 41, main water supply pipe; 42, water supply pump; 43, auxiliary water supply pipe; 5, first bypass; 6, second bypass; 7, steam supply pipe; 8, industrial steam pipe; 9, steam inlet pipe; 10, high-pressure superheated steam pipe; 11, steam extraction valve; 12, first valve; 13, second valve; 14, first bypass valve; 15, third valve; 16, fourth valve; 17, second bypass valve; 18, steam supply valve; 19, industrial steam valve; 20, high-pressure superheated steam valve. DETAILED DESCRIPTION

[0031] The technical solutions of the present application will be described below in conjunction with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative work based on these drawings also belong to the protection scope of the present application.

[0032] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "mounting", "connection", "linking" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] As shown in Figure 1 The embodiment of the present application provides a solid and molten salt heat storage system for combined heat and power peak shaving, which comprises a steam turbine unit 1, a high-temperature solid heat storage subsystem 2, a low-temperature molten salt heat storage subsystem 3 and a water supplementing subsystem 4. When the actual power generation is less than the power generation of grid scheduling, the high-temperature solid heat storage subsystem 2 and the low-temperature molten salt heat storage subsystem 3 store heat. When the actual power generation is greater than the power generation of grid scheduling, the high-temperature solid heat storage subsystem 2 and the low-temperature molten salt heat storage subsystem 3 release heat, heat water into high-temperature steam and supply the high-temperature steam to the steam turbine unit 1 to increase the power generation capacity of the steam turbine unit 1. Specifically, the high-temperature solid heat storage subsystem can be used to store heat energy of 500-1200℃ or above, and the low-temperature molten salt heat storage subsystem 3 can be used to store heat energy of 150-600℃, so that the generated steam can match the steam temperature required by the steam turbine unit 1.

[0035] Specifically, the steam turbine unit 1 comprises a steam turbine high-pressure cylinder 101, a steam reheater 102 and a steam turbine low-pressure cylinder 103. The steam outlet of the boiler is connected with the steam inlet of the steam turbine high-pressure cylinder 101. The steam outlet of the steam turbine high-pressure cylinder 101 is connected with the steam inlet of the steam reheater 102. The steam outlet of the steam turbine low-pressure cylinder 103 is connected with a condenser. The steam outlet of the steam superheater 23 is connected with the steam inlet of the steam turbine high-pressure cylinder 101.

[0036] Specifically, the high-temperature solid heat storage subsystem 2 comprises a high-temperature solid heat storage device 21, a high-temperature fan 22 and a steam superheater 23. The high-temperature solid heat storage device 21 stores heat through electric heating. The air outlet of the high-temperature solid heat storage device 21 is communicated with the air inlet of the high-temperature fan 22. The air outlet of the high-temperature fan 22 is communicated with the air inlet of the steam superheater 23. The air outlet of the steam superheater 23 is communicated with the air inlet of the high-temperature solid heat storage device 21. The high-temperature solid heat storage device 21 stores heat through electric heating, which generally uses valley power of the power grid or excess power of new energy consumption to realize heat storage. Specifically, in the heat releasing process, the gaseous medium circulates and flows under the driving of the high-temperature fan 22, exchanges heat in the high-temperature solid heat storage device 21, then releases heat in the steam superheater 23 to heat the steam in the steam superheater 23. The steam superheater 23 and the steam inlet of the steam turbine high-pressure cylinder 101 are communicated with a high-pressure superheated steam pipe 10. The high-pressure superheated steam pipe 10 is communicated with a high-pressure superheated steam valve 20.

[0037] Specifically, the low-temperature molten salt heat storage subsystem 3 comprises a low-temperature molten salt hot tank 31, a molten salt heat-releasing steam generator 33, a molten salt heat-releasing make-up water heater 34, a low-temperature molten salt cold tank 35, and a low-temperature molten salt heating assembly. The molten salt outlet of the low-temperature molten salt hot tank 31 is provided with a molten salt high-temperature circulating pump 32. The molten salt outlet of the molten salt high-temperature circulating pump 32 is in communication with the molten salt inlet of the molten salt heat-releasing steam generator 33. The molten salt outlet of the molten salt heat-releasing steam generator 33 is in communication with the molten salt inlet of the molten salt heat-releasing make-up water heater 34. The molten salt outlet of the molten salt heat-releasing make-up water heater 34 is in communication with the molten salt inlet of the low-temperature molten salt cold tank 35. The molten salt outlet of the low-temperature molten salt cold tank 35 is in communication with the molten salt inlet of the low-temperature molten salt heating assembly. The molten salt inlet of the low-temperature molten salt heating assembly is provided with a molten salt low-temperature circulating pump 36. The molten salt outlet of the low-temperature molten salt heating assembly is connected to the molten salt inlet of the low-temperature molten salt hot tank 31.

[0038] Specifically, the low-temperature molten salt heating assembly comprises a low-temperature molten salt electric heater 37 and a low-temperature molten salt steam heater 38. The molten salt inlet of the low-temperature molten salt electric heater 37 is in communication with the molten salt outlet of the molten salt low-temperature circulating pump 36. The molten salt outlet of the low-temperature molten salt electric heater 37 is in communication with the molten salt inlet of the low-temperature molten salt steam heater 38. The molten salt outlet of the low-temperature molten salt steam heater 38 is in communication with the molten salt inlet of the low-temperature molten salt hot tank 31. A first bypass 5 is in communication between the molten salt inlet and the molten salt outlet of the low-temperature molten salt electric heater 37. The molten salt inlet and the molten salt outlet of the low-temperature molten salt electric heater 37 are respectively provided with a first valve 12 and a second valve 13. A first bypass valve 14 is arranged on the first bypass 5. A second bypass 6 is in communication between the molten salt inlet and the molten salt outlet of the low-temperature molten salt steam heater 38. The molten salt inlet and the molten salt outlet of the low-temperature molten salt steam heater 38 are respectively provided with a third valve 15 and a fourth valve 16. A second bypass valve 17 is arranged on the second bypass 6.

[0039] Specifically, the reheat steam outlet of the steam reheater 102 and the steam inlet of the low-temperature molten salt steam heater 38 are in communication with a steam inlet pipe 9. A steam extraction valve 11 is arranged on the steam inlet pipe 9. The steam extraction valve 11 is located at the steam outlet of the steam reheater 102.

[0040] During heat storage, the molten salt heat release steam generator 33 and the molten salt heat release makeup water heater 34 are not operating in the low-temperature molten salt hot tank 31, low-temperature molten salt cold tank 35, low-temperature molten salt electric heater 37, and low-temperature molten salt steam heater 38 are operating. Molten salt can be stored through electric heating or steam heating. Specifically, when using electric heating, the first valve 12, the second valve 13, and the second bypass valve 17 are open, while the third valve 15, the fourth valve 16, the first bypass valve 14, and the extraction steam valve 11 are closed. The molten salt low-temperature circulating pump 36 is started. Molten salt in the molten salt cold tank 35 is heated by the low-temperature molten salt electric heater 37 and then stored in the low-temperature molten salt hot tank 31. When steam heating is used, the third valve 15, the fourth valve 16, the first bypass valve 14 and the extraction valve 11 are opened, and the first valve 12, the second valve 13 and the second bypass valve 17 are closed. The molten salt low-temperature circulation pump 36 is started, and the molten salt in the low-temperature molten salt cold tank 35 is heated by the low-temperature molten salt steam heater 38 and then stored in the low-temperature molten salt hot tank 31. Specifically, the electricity used for electric heating is generally off-peak electricity from the power grid, which is low in cost.

[0041] When the low-temperature molten salt heat storage subsystem 3 releases heat, the low-temperature molten salt electric heater 37 and the low-temperature molten salt steam heater 38 do not operate, that is, the low-temperature molten salt heating components do not operate. The low-temperature molten salt hot tank 31, the molten salt heat release steam generator 33, the molten salt heat release water heater 34 and the low-temperature molten salt cold tank 35 operate, the molten salt high-temperature circulation pump 32 starts, and the molten salt in the low-temperature molten salt hot tank 31 enters the molten salt heat release steam generator 33 and the molten salt heat release water heater 34 in sequence to exchange heat with water, and then enters the low-temperature molten salt cold tank 35 for storage, forming a molten salt heat release circuit.

[0042] Specifically, the outlet of the water supply subsystem 4, the molten salt heat release water heater 34, the molten salt heat release steam generator 33, the steam superheater 23, and the steam inlet of the turbine unit 1 are sequentially connected to form a steam supply circuit. Specifically, the water supply subsystem 4 includes a main water supply pipe 41 and a water supply pump 42. The water supply pump 42 is connected to the water supply pipe, and the outlet of the water supply pump 42 is connected to the inlet of the molten salt heat release water heater 34. When the high-temperature solid heat storage subsystem 2 and the low-temperature molten salt heat storage subsystem 3 release heat, the water supply pump 42 starts, and the water passes through the molten salt heat release water heater 34, the molten salt heat release steam generator 33, and the steam superheater 23 in sequence to be heated into superheated steam, and finally enters the steam inlet of the high-pressure cylinder 101 of the turbine for power generation.

[0043] Specifically, the water replenishment subsystem 4 also includes a secondary water replenishment pipe 43. The inlet of the secondary water replenishment pipe 43 is connected to the outlet of the low-temperature molten salt heating component. The inlet of the secondary water replenishment pipe 43 is connected to the main water replenishment pipe 41 and is located at the inlet of the water replenishment pump 42. When the low-temperature molten salt heat storage subsystem 3 uses steam for heat storage, the steam after heat exchange forms hot water that enters the secondary water replenishment pipe 43 and then enters the main water replenishment pipe 41 for storage. It can be reused when the high-temperature solid heat storage subsystem 2 and the low-temperature molten salt heat storage subsystem 3 release heat.

[0044] Specifically, a steam supply pipe 7 connects the steam inlet of the steam superheater 23 and the steam outlet of the molten salt heat release steam generator 33. An industrial steam pipe 8 is connected to the steam supply pipe 7, and a steam supply valve 18 is connected to the steam supply pipe 7 and located at the steam inlet of the steam superheater 23. An industrial steam valve 19 is connected to the industrial steam pipe 8, which provides steam to industrial steam users. When the high-temperature solid heat storage subsystem 2 and the low-temperature molten salt heat storage subsystem 3 release heat, industrial steam users need to supply steam. At this time, the industrial steam valve 19 and the steam supply valve 18 are opened. A portion of the steam is heated by the steam superheater 23 and then enters the high-pressure cylinder 101 of the steam turbine for power generation. A portion of the steam enters the industrial steam pipe 8 to supply steam to industrial steam users. If industrial steam users do not need to supply steam, the industrial steam valve 19 is closed and the steam supply valve 18 is opened. All the steam enters the steam turbine unit 1 for power generation. Of course, if only industrial steam users need to supply steam and peak shaving is not required, only the industrial steam valve 19 needs to be opened to run the molten salt heat release circuit.

[0045] In summary, a method for a solid and molten salt thermal storage system for peak shaving in combined heat and power (CHP) includes the following steps:

[0046] When the system participates in power peak shaving, when the actual power generation is greater than the grid dispatch power generation, it enters the heat storage working condition, the high-temperature solid heat storage subsystem 2 uses the grid valley electricity to store heat, specifically, when the degree electricity cost corresponding to the high position operation of the boiler is higher than the purchase of real-time valley electricity degree electricity price, then deep peak shaving is performed by reducing the boiler evaporation capacity, the high-temperature solid heat storage subsystem uses the purchased valley electricity to store heat, otherwise the steam turbine unit 1 itself generates electricity to store heat; the low-temperature molten salt heat storage subsystem 3 uses the steam or electricity of the boiler to store heat, specifically, at this time the molten salt heat-releasing steam generator 33 and the molten salt heat-releasing water supply heater 34 do not operate, when the boiler maintains a high heat power level operation, the steam quantity is sufficient, and the steam turbine unit operates safely, the reheated steam extraction quantity is allowed to be increased, the extraction valve 11 is opened, the low-temperature molten salt heat storage subsystem 3 uses the steam of the boiler to store heat, at this time the third valve 15, the fourth valve 16 and the first bypass valve 14 are opened, the first valve 12, the second valve 13 and the second bypass valve 17 are closed, the molten salt low-temperature circulating pump 36 is started, the molten salt in the low-temperature molten salt cold tank 35 is heated by the low-temperature molten salt steam heater 38 and then stored in the low-temperature molten salt hot tank 31; when the high position operation cost of the boiler is higher than the purchase of real-time valley electricity degree electricity price, then deep peak shaving is performed by reducing the boiler evaporation capacity, electric heating is used, at this time the first valve 12, the second valve 13 and the second bypass valve 17 are opened, the third valve 15, the fourth valve 16, the first bypass valve 14 and the extraction valve 11 are closed, the molten salt low-temperature circulating pump 36 is started, the molten salt in the low-temperature molten salt cold tank 35 is heated by the low-temperature molten salt electric heater 37 and then stored in the low-temperature molten salt hot tank 31.

[0047] When the system participates in power peak shaving, when the actual power generation is less than the grid dispatch power generation, it enters the heat-releasing working condition, the water supply pump 42 is started, the water in the water supply pipe is heated by the low-temperature molten salt heat storage subsystem 3 and the high-temperature solid heat storage subsystem 2 at the same time to release heat to become superheated steam, the water is heated to become high-temperature steam to supply the steam turbine unit 1 to generate electricity; specifically, the low-temperature molten salt heat storage subsystem 3 releases heat, the low-temperature molten salt heating assembly does not operate, the molten salt high-temperature circulating pump 32 is started, the molten salt in the low-temperature molten salt hot tank 31 enters the molten salt heat-releasing steam generator 33 and the molten salt heat-releasing water supply heater 34 in turn to exchange heat with water, and then is stored in the low-temperature molten salt cold tank 35, the water is heated to become steam from the molten salt heat-releasing steam generator 33 into the steam supply pipe 7, and then into the steam superheater 23, at this time the high-temperature solid heat storage subsystem 2 releases heat, under the driving of the high-temperature fan 22, the gas medium circulates and flows, exchanges heat in the high-temperature solid heat storage 21, and then releases heat in the steam superheater 23 to heat the steam in the steam superheater 23, the steam is heated to become superheated steam, the temperature reaches one thousand degrees or even higher, so that the generated steam can match the steam temperature required by the steam turbine unit 1, the quality of the steam supplied to the steam turbine unit 1 to generate electricity is higher, and the power generation efficiency of the steam turbine unit 1 is higher.

[0048] Specifically, in the heat-releasing working condition, if the industrial steam user needs steam supply, at this time, the industrial steam valve 19 and the steam supply valve 18 are opened, a part of the steam is heated by the steam superheater 23 and then enters the high-pressure cylinder 101 of the steam turbine to generate electricity, and the other part of the steam enters the industrial steam pipe 8 to supply steam to the industrial steam user. The steam flow of each can be controlled by controlling the opening degree of the industrial steam valve 19 and the steam supply valve 18. If the industrial steam user does not need steam supply, at this time, the industrial steam valve 19 is closed and the steam supply valve 18 is opened, and all the steam enters the steam turbine unit 1 to generate electricity.

[0049] Of course, when the system does not participate in peak regulation, if the industrial steam user needs steam supply, only the industrial steam valve 19 needs to be opened, and the molten salt heat-releasing circuit is run. Specifically, the low-temperature molten salt heat storage subsystem 3 releases heat, the low-temperature molten salt heating assembly does not run, the molten salt high-temperature circulating pump 32 is started, the molten salt in the low-temperature molten salt hot tank 31 is sequentially heated with water in the molten salt heat-releasing steam generator 33 and the molten salt heat-releasing water supply heater 34, and then is stored in the low-temperature molten salt cold tank 35. The water is heated into steam from the molten salt heat-releasing steam generator 33 into the steam supply pipe 7, and then into the industrial steam pipe 8 to supply steam to the industrial steam user.

[0050] The method runs the high-temperature solid heat storage subsystem 2 and the low-temperature molten salt heat storage subsystem 3 which are isolated from each other, can be used for storing heat energy in different temperature ranges, the low-temperature molten salt heat storage subsystem 3 can be used for storing heat energy of 150℃-500℃, the energy stored by the low-temperature molten salt heat storage subsystem 3 can realize industrial steam production, the high-temperature solid heat storage subsystem 2 can be used for storing heat energy of 500℃-1200℃ or above, cooperates with the low-temperature molten salt heat storage subsystem 3 to realize the re-preparation of high-temperature and high-pressure steam, and is fed into the high-pressure cylinder 101 of the steam turbine, improves the steam flow of the high-pressure cylinder of the cogeneration unit, improves the power generation capacity of the unit, realizes the temperature matching of the heat storage system, improves the wide temperature range stable operation ability of the system, strengthens the operation efficiency of the system, and strengthens the thermal and electrical decoupling ability of the cogeneration unit.

[0051] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application. Any non-essential changes and replacements made by those skilled in the art on the basis of the present application all belong to the protection scope of the present application.

Claims

1. A solid and molten salt thermal energy storage system for combined heat and power peak shaving, characterized by, The system comprises a steam turbine unit, a high-temperature solid heat storage subsystem, a low-temperature molten salt heat storage subsystem and a water supply subsystem, wherein the steam inlet of the steam turbine unit is communicated with the steam outlet pipe of the boiler; The high-temperature solid heat storage subsystem comprises a high-temperature solid heat storage device, a high-temperature fan and a steam superheater, the high-temperature solid heat storage device is heated by electricity, the air outlet of the high-temperature solid heat storage device is communicated with the air inlet of the high-temperature fan, the air outlet of the high-temperature fan is communicated with the air inlet of the steam superheater, and the air outlet of the steam superheater is communicated with the air inlet of the high-temperature solid heat storage device; The low-temperature molten salt heat storage subsystem comprises a low-temperature molten salt hot tank, a molten salt heat-releasing steam generator, a molten salt heat-releasing water supply heater, a low-temperature molten salt cold tank and a low-temperature molten salt heating assembly, the molten salt outlet of the low-temperature molten salt hot tank is provided with a molten salt high-temperature circulating pump, the molten salt outlet of the molten salt high-temperature circulating pump is communicated with the molten salt inlet of the molten salt heat-releasing steam generator, the molten salt outlet of the molten salt heat-releasing steam generator is communicated with the molten salt inlet of the molten salt heat-releasing water supply heater, the molten salt outlet of the molten salt heat-releasing water supply heater is communicated with the molten salt inlet of the low-temperature molten salt cold tank, the molten salt outlet of the low-temperature molten salt cold tank is communicated with the molten salt inlet of the low-temperature molten salt heating assembly, the molten salt inlet of the low-temperature molten salt heating assembly is provided with a molten salt low-temperature circulating pump, and the molten salt outlet of the low-temperature molten salt heating assembly is connected with the molten salt inlet of the low-temperature molten salt hot tank; The water outlet of the water supply subsystem, the molten salt heat-releasing water supply heater, the molten salt heat-releasing steam generator, the steam superheater and the steam inlet of the high-pressure cylinder in the steam turbine unit are sequentially communicated to form a steam supply circuit; The steam inlet of the low-temperature molten salt heating assembly is communicated with the reheated steam outlet of the steam turbine unit for heating the low-temperature molten salt; An industrial steam pipe is communicated between the steam pipeline between the steam inlet of the steam superheater and the steam outlet of the molten salt heat-releasing steam generator, and the industrial steam pipe provides steam for industrial steam users; When the system participates in peak regulation, the low-temperature molten salt heat storage subsystem and the high-temperature solid heat storage subsystem are in heat-releasing conditions, and when industrial steam is used for steam supply, part of the steam is heated by the steam superheater and then enters the steam turbine unit to generate power, and part of the steam enters the industrial steam pipe to supply steam for industrial steam users; When the system does not participate in peak regulation, the industrial steam users need steam supply, the low-temperature molten salt heat storage subsystem is in a heat-releasing condition, the steam sequentially heated by the molten salt heat-releasing water supply heater and the molten salt heat-releasing steam generator is all supplied into the industrial steam pipe to provide steam for industrial steam users, and the high-temperature heat storage subsystem does not operate.

2. The solid and molten salt thermal energy storage system of claim 1, wherein, The low-temperature molten salt heating assembly comprises a low-temperature molten salt electric heater and a low-temperature molten salt steam heater, a molten salt inlet of the low-temperature molten salt electric heater is communicated with a molten salt outlet of the low-temperature molten salt circulating pump, a molten salt outlet of the low-temperature molten salt electric heater is communicated with a molten salt inlet of the low-temperature molten salt steam heater, and a molten salt outlet of the low-temperature molten salt steam heater is communicated with a molten salt inlet of the low-temperature molten salt hot tank; a first bypass is communicated between the molten salt inlet and the molten salt outlet of the low-temperature molten salt electric heater, and a second bypass is communicated between the molten salt inlet and the molten salt outlet of the low-temperature molten salt steam heater.

3. The solid and molten salt thermal energy storage system of claim 1, wherein, The water supplement subsystem comprises a main water supplement pipe and a water supplement pump, the water supplement pump is communicated with the water supplement pipe, and a water outlet of the water supplement pump is communicated with a water inlet of the molten salt heat-releasing water supplement heater.

4. The solid and molten salt thermal energy storage system of claim 3, wherein, The water supplement subsystem further comprises a secondary water supplement pipe, a water inlet of the secondary water supplement pipe is communicated with a water outlet of the low-temperature molten salt heating assembly, the water inlet of the secondary water supplement pipe is communicated with the main water supplement pipe, and is located at a water inlet of the water supplement pump.

5. The solid and molten salt thermal energy storage system of claim 1, wherein, The steam turbine unit comprises a steam turbine high-pressure cylinder, a steam reheater and a steam turbine low-pressure cylinder, a steam outlet of the boiler is connected with a steam inlet of the steam turbine high-pressure cylinder, a steam outlet of the steam turbine high-pressure cylinder is connected with a steam inlet of the steam reheater, a steam outlet of the steam reheater is connected with a steam inlet of the steam turbine low-pressure cylinder, and a steam outlet of the steam turbine low-pressure cylinder is connected with a condenser; a steam outlet of the steam superheater is connected with a steam inlet of the steam turbine high-pressure cylinder, and a reheated steam outlet of the steam reheater is communicated with a steam inlet of the low-temperature molten salt heating assembly.

6. The method for a solid and molten salt thermal energy storage system for combined heat and power peak shaving according to any one of claims 1-5, characterized in that, The method comprises the following steps: When the system participates in power peak regulation, if the actual power generation is greater than the power grid dispatching power generation, the system enters the heat storage working condition, the low-temperature molten salt heat storage subsystem stores heat by using the steam of the boiler or electric energy, and the high-temperature solid heat storage subsystem stores heat by using electric energy; When the system participates in power peak regulation, if the actual power generation is less than the power grid dispatching power generation, the system enters the heat releasing working condition, the water supplement subsystem supplements water, and the low-temperature molten salt heat storage subsystem and the high-temperature solid heat storage subsystem release heat at the same time, so as to heat water into high-temperature steam to supply the steam turbine unit to generate power.

7. A method for a solid and molten salt thermal energy storage system for combined heat and power peak shaving according to claim 6, characterized in that, When the system participates in power peak regulation, if the actual power generation is greater than the power grid dispatching power generation, the low-temperature molten salt circulating pump is started, the molten salt in the low-temperature molten salt cold tank is heated by using electric energy or the steam of the boiler through the low-temperature molten salt heating assembly, and then is stored in the low-temperature molten salt hot tank, and the high-temperature solid heat storage subsystem stores heat by using electric energy.

8. A method for a solid and molten salt thermal energy storage system for combined heat and power peak shaving according to claim 7, characterized in that, When the system participates in power peak regulation, if the actual power generation is greater than the power grid dispatching power generation, when the boiler maintains a high heat power level to run, the steam quantity is sufficient, and the unit operation is safe, the molten salt in the low-temperature molten salt cold tank is heated by using the steam of the boiler through the low-temperature molten salt heating assembly; When the cost of high-level operation of the boiler is higher than the price of real-time valley electricity, the system carries out deep peak shaving by reducing the evaporation amount of the boiler, and the molten salt in the low-temperature molten salt cold tank is heated by the low-temperature molten salt heating assembly using the purchased valley electricity. When the cost of high-level operation of the boiler is higher than the price of real-time valley electricity, the system carries out deep peak shaving by reducing the evaporation amount of the boiler, and the molten salt in the low-temperature molten salt cold tank is heated by the low-temperature molten salt heating assembly using the purchased valley electricity.

9. The method for solid and molten salt thermal energy storage system for combined heat and power peak shaving of claim 6, wherein, When the system participates in power peak shaving, when the actual power generation is less than the power grid dispatching power generation, it enters the heat release working condition, the molten salt high-temperature circulating pump starts, the high-temperature molten salt in the low-temperature molten salt hot tank enters the molten salt heat release steam generator and the molten salt heat release water supply heater in turn and exchanges heat with water, and then enters the low-temperature molten salt cold tank; the high-temperature fan starts to drive the gas to cool the high-temperature solid heat storage medium in the high-temperature solid heat accumulator and bring the heat into the steam superheater; at the same time, the water supply in the water supply subsystem enters the steam turbine set to generate electricity after being heated by the molten salt heat release steam generator, the molten salt heat release water supply heater and the steam superheater.

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