A system and method for improving the efficiency and reliability of molten salt thermal storage energy utilization

Abstract

The present invention relates to the field of molten salt heat storage technology, and in particular to a system and method for improving the energy utilization efficiency and reliability of molten salt heat storage. The system comprises a single-tank molten salt heat storage device, a modular molten salt heat storage device, an external heater, a primary heat exchanger, a built-in heater, and a deaerator. The system utilizes a method for restoring molten salt without an external steam heat source. Through the coordinated adjustment of the built-in heater and the external heater, the solidified molten salt in the modular heat storage device and the single-tank molten salt heat storage device is melted, thereby enhancing the flexibility of the modular molten salt heat storage device in situations where a stable heat source is not available. Furthermore, through the clever coordination of the deaerator, the primary heat exchanger, and other components, the energy utilization efficiency of the modular molten salt heat storage device is significantly improved. This system addresses the low efficiency and poor flexibility of modular molten salt heat storage devices in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of molten salt heat storage, and in particular to a system and method for improving the energy utilization efficiency and reliability of molten salt heat storage. Background Art

[0002] Amidst the increasingly severe challenges of global warming and the dwindling supply of non-renewable energy, the exploration and innovation of renewable energy are booming at an unprecedented pace. This progress not only reflects humanity's urgent pursuit of sustainable development, but also reveals the limitations of traditional industries in energy efficiency. Inefficient energy conversion and consumption models are no longer able to meet the high demands of modern society for clean energy. At the same time, while natural energy sources such as solar and wind power hold enormous potential, their inherent intermittent and unstable nature remains a key obstacle to their widespread adoption.

[0003] In the face of these challenges, the rise of energy storage technology has become indispensable. Energy storage systems can effectively compensate for the temporal and spatial mismatch between energy supply and demand, ensuring stable power delivery to the grid even when sunlight is insufficient or wind speeds are weak. Whether for home or industrial applications, from electric vehicle battery packs to large-scale pumped-storage power plants, energy storage solutions are dedicated to smoothing energy fluctuations and ensuring the continuity and reliability of energy supply, thereby promoting the widespread adoption of renewable energy, accelerating the pace of global energy transformation, and laying a solid foundation for building a clean, efficient, and sustainable energy future.

[0004] This reliance on energy storage technology is not only a necessary means of resolving the contradiction between energy supply and demand, but also a key driver of the development of a green, low-carbon economy. With the continuous advancement of energy storage technology, we have reason to believe that a more balanced and greener energy system is gradually taking shape, contributing the power of science and technology to protecting the Earth's ecological environment.

[0005] Molten salt thermal storage technology, with its high thermal storage capacity, long thermal storage time, high thermal storage efficiency, rapid speed, safety, reliability, and long service life, is gradually emerging in the energy storage technology field, becoming a major highlight in the thermal power generation flexibility upgrade and industrial steam market. Molten salt thermal storage technology, also known as molten salt thermal energy storage technology, is a method of storing and releasing thermal energy at high temperatures using molten salts. As an independent energy storage unit, the molten salt energy storage system can precisely meet the needs of increasing thermal power generation flexibility and industrial steam production. Integrating high-capacity molten salt energy storage modules into thermal power units can achieve decoupled operation of heat and electricity, with energy conversion efficiency comparable to pumped hydro storage, helping thermal power units expand their low-load operating range to 20%. This not only broadens the revenue channels for power ancillary services, but also increases the economic benefits of steam production.

[0006] Existing modular molten salt thermal storage systems use molten salt and solid oxide as the heat storage medium, and utilize built-in heat exchangers. The molten salt flows slowly within the module, resulting in poor heat exchange efficiency during heat release. This can lead to incomplete heat release during the heat release phase. This means the stored energy cannot be fully utilized, reducing the overall efficiency of the system. The molten salt in modular molten salt thermal storage systems faces the risk of solidification due to uneven temperature distribution within the tank, complex systems, and the risk of solidification, especially when the temperature drops below its melting point. Once the molten salt solidifies, it not only poses a safety hazard but can also cause blockages in pipelines and valves, obstructing the flow of the medium and preventing the entire circulation system from operating normally. This not only affects system efficiency but can also cause system downtime, impacting production and energy supply. To quickly melt the solidified molten salt, additional energy, such as steam, is required to reheat it to a liquid state, resulting in low efficiency and limited flexibility. Summary of the Invention

[0007] In response to the problems of low efficiency and poor flexibility of modular molten salt heat storage devices in the prior art, the present invention provides a system and method for improving the efficiency and reliability of molten salt heat storage energy utilization.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The present invention provides a system for improving the utilization efficiency and reliability of molten salt heat storage energy, comprising a single-tank molten salt heat storage device, a modular molten salt heat storage device, an external heater, a primary heat exchanger and a deaerator;

[0010] The single-tank molten salt heat storage device is provided with a built-in heater for melting the solidified molten salt in the single-tank molten salt heat storage device; the molten salt output end of the single-tank molten salt heat storage device is sequentially connected to a primary heat exchanger, an external heater and a modular molten salt heat storage device;

[0011] The molten salt output end of the modular molten salt heat storage device is connected to the first molten salt input end of the single-tank molten salt heat storage device;

[0012] The high-temperature desalted water output end of the deaerator is connected in sequence to the primary heat exchanger and the built-in heater of the modular molten salt heat storage device, and the steam output end of the built-in heater of the modular molten salt heat storage device is connected to the steam input end of the deaerator and the user;

[0013] The molten salt output end of the primary heat exchanger is also connected to the second molten salt input end of the single-tank molten salt heat storage device.

[0014] Furthermore, a molten salt circulation pump is provided between the molten salt output end of the single-tank molten salt heat storage device and the molten salt input end of the primary heat exchanger, and the molten salt circulation pump is a variable frequency pump.

[0015] Furthermore, a water feed pump is provided between the high-temperature desalted water output end of the deaerator and the water input end of the primary heat exchanger, and the water feed pump is a variable frequency pump.

[0016] Furthermore, a molten salt recycling valve is provided between the molten salt output end of the primary heat exchanger and the second molten salt input end of the single-tank molten salt heat storage device.

[0017] Furthermore, a molten salt heating valve is provided between the molten salt output end of the first-stage heat exchanger and the molten salt input end of the external heater.

[0018] Furthermore, a molten salt heat storage heating steam heating return valve is provided between the steam output end of the built-in heater of the modular molten salt heat storage device and the steam input end of the deaerator.

[0019] Furthermore, a molten salt heat storage device heating valve is provided on the external steam supply pipeline connecting the steam output end of the built-in heater of the modular molten salt heat storage device to the user.

[0020] Furthermore, the modular molten salt heat storage device includes a plurality of modular molten salt heat storage units with built-in heaters connected in series, and adjacent modular molten salt heat storage units are connected through module connecting pipes.

[0021] Furthermore, the molten salt output end of the modular molten salt heat storage device is connected to the first molten salt input end of the single-tank molten salt heat storage device through a device connecting pipe.

[0022] The present invention also provides a method for improving the efficiency and reliability of molten salt thermal storage energy utilization using the above system, comprising:

[0023] When storing heat:

[0024] The molten salt in the single-tank molten salt heat storage device is transported to an external heater through a primary heat exchanger for heating and converted into high-temperature molten salt;

[0025] The high-temperature molten salt is transported to the modular molten salt heat storage device for heat storage, and overflows into the single-tank molten salt heat storage device to complete the heat storage process;

[0026] When releasing heat:

[0027] The high-temperature molten salt stored in the single-tank molten salt heat storage device is transported to the first-stage heat exchanger for heat exchange;

[0028] A portion of the molten salt after heat exchange is heated by an external heater and then transported to the modular molten salt heat storage device, and overflows into the single-tank molten salt heat storage device, while the other portion of the molten salt is directly transported back to the single-tank molten salt heat storage device;

[0029] The high-temperature desalted water in the deaerator is transported to the primary heat exchanger for heat exchange with the molten salt entering the primary heat exchanger;

[0030] The high-temperature desalted water after heat exchange is transported to the heat exchange steam coil in the modular molten salt heat storage device, and the heat stored in the modular molten salt heat storage device is used to produce high-temperature steam;

[0031] A portion of the high-temperature steam is transported to the deaerator to heat the desalted water, and the other portion of the steam is transported to the user for heating, completing the heat release process.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a system for improving the utilization efficiency and reliability of molten salt heat storage energy, comprising a single-tank molten salt heat storage device, a modular molten salt heat storage device, an external heater, a primary heat exchanger, a built-in heater and a deaerator; the system adopts a method of restoring the melting of molten salt without an external steam heat source. When the molten salt inside the single-tank molten salt heat storage device solidifies, the built-in heater can be started to heat so that the molten salt in the single-tank molten salt heat storage device is completely converted from a solid state to a molten state, and then the molten salt at the bottom of the single-tank molten salt heat storage device is recycled back to the top of the single-tank molten salt heat storage device through the primary heat exchanger. At the same time, the desalted water in the deaerator is heated through the primary heat exchanger and then transported to the heat exchange steam coil of the modular molten salt heat storage device for heat exchange with the molten salt and a solid heat storage medium, and the high-temperature steam after heat exchange is transported back to the deaerator. When the molten salt in the modular molten salt heat storage device is converted from a solid state to a molten state, the system resumes operation. The system melts the solidified molten salt within the modular heat storage device and the single-tank molten salt heat storage device through the coordinated adjustment of the internal and external heaters. This enhances the flexibility of the modular molten salt heat storage device in situations where a stable heat source is unavailable. Furthermore, the energy efficiency of the modular molten salt heat storage device is significantly improved through the clever coordination of the deaerator and a heat exchanger. The system boasts a simple structure, excellent flexibility, low modification costs, and high energy efficiency.

[0034] A molten salt circulation pump is provided between the molten salt output end of the single-tank molten salt heat storage device and the molten salt input end of the primary heat exchanger. The molten salt circulation pump is a variable frequency pump, which pumps the molten salt of the single-tank molten salt heat storage device to the primary heat exchanger and the external heater, and adjusts the outlet temperature of the external heater and the liquid level on the water side of the primary heat exchanger through frequency conversion.

[0035] A water feed pump is provided between the high-temperature desalted water output end of the deaerator and the water input end of the primary heat exchanger. The water feed pump is a variable frequency pump, which is used to pump the desalted water in the deaerator to the primary heat exchanger for heat exchange and adjust the water flow by frequency conversion.

[0036] A molten salt recirculation valve is provided between the molten salt output end of the primary heat exchanger and the second molten salt input end of the single-tank molten salt heat storage device, and the outlet steam temperature of the modular molten salt heat storage device can be adjusted by adjusting its opening.

[0037] A molten salt heating valve is provided between the molten salt output end of the primary heat exchanger and the molten salt input end of the external heater, for adjusting the flow of molten salt entering the external heater.

[0038] A molten salt heat storage heating steam heating return valve is provided between the steam output end of the built-in heater of the modular molten salt heat storage device and the steam input end of the deaerator to control the steam input amount.

[0039] A molten salt heat storage device heating valve is provided on the external steam supply pipeline connecting the steam output end of the built-in heater of the modular molten salt heat storage device to the user, which is used to adjust the heat supply input to the user.

[0040] The modular molten salt heat storage device includes several modular molten salt heat storage units with built-in heaters connected in series. Adjacent modular molten salt heat storage units are connected by module connecting pipes. By storing heat step by step, the temperature uniformity inside the heat storage device can be effectively improved, thereby improving the heat storage efficiency and heat storage duration.

[0041] The present invention also provides a method for improving the utilization efficiency and reliability of molten salt heat storage energy by using the above system, wherein the molten salt in the single-tank molten salt heat storage device is transported to an external heater for heating through a primary heat exchanger to be converted into high-temperature molten salt, and is transported to a modular molten salt heat storage device for heat storage, and overflows into the single-tank molten salt heat storage device to complete the heat storage process with high heat storage efficiency; the high-temperature molten salt stored in the single-tank molten salt heat storage device is transported to a primary heat exchanger for heat exchange; a portion of the molten salt after heat exchange is heated by an external heater, and is transported to the modular molten salt heat storage device, and overflows into In the single-tank molten salt heat storage device, the other part of the molten salt is directly transported back to the single-tank molten salt heat storage device; the high-temperature desalted water in the deaerator is transported to the first-stage heat exchanger for heat exchange with the molten salt entering the first-stage heat exchanger; the high-temperature desalted water after heat exchange is transported to the heat exchange steam coil in the modular molten salt heat storage device, and high-temperature steam is produced using the heat stored in the modular molten salt heat storage device; a part of the high-temperature steam is transported to the deaerator to heat the desalted water, and the other part of the steam is transported to the user for heating, completing the heat release process, with high energy utilization rate, no need for an external steam heat source, simple method and good flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of a system for improving the efficiency and reliability of molten salt thermal storage energy utilization according to the present invention.

[0043] Figure 2 The present invention is a flow chart of a method for improving the efficiency and reliability of molten salt thermal storage energy utilization.

[0044] Among them, 1-water feed pump, 2-single-tank molten salt heat storage device, 3-molten salt heat storage heating steam heating return valve, 4-modular molten salt heat storage device, 5-built-in heater, 6-device connecting pipe, 7-molten salt circulation pump, 8-external heater, 9-module connecting pipe, 10-first-stage heat exchanger, 11-molten salt heat storage device heating valve, 12-deaerator, 13-molten salt recirculation valve, 14-molten salt heating valve. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0047] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0048] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0049] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0050] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0051] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0052] See also Figure 1 , the present invention provides a system for improving the utilization efficiency and reliability of molten salt heat storage energy, comprising a single-tank molten salt heat storage device 2, a modular molten salt heat storage device 4, an external heater 8, a primary heat exchanger 10 and a deaerator 12;

[0053] The single-tank molten salt heat storage device 2 is provided with a built-in heater 5 for melting the solidified molten salt in the single-tank molten salt heat storage device 2; the molten salt output end of the single-tank molten salt heat storage device 2 is connected in sequence to the primary heat exchanger 10, the external heater 8 and the modular molten salt heat storage device 4;

[0054] The molten salt output end of the modular molten salt heat storage device 4 is connected to the first molten salt input end of the single-tank molten salt heat storage device 2;

[0055] The high-temperature desalted water output end of the deaerator 12 is connected in sequence to the primary heat exchanger 10 and the built-in heater of the modular molten salt heat storage device 4, and the steam output end of the built-in heater of the modular molten salt heat storage device 4 is connected to the steam input end of the deaerator 12 and the user;

[0056] The molten salt output end of the primary heat exchanger 10 is also connected to the second molten salt input end of the single-tank molten salt heat storage device 2 .

[0057] The system uses a method of restoring the melting of molten salt without an external steam heat source. When the molten salt inside the single-tank molten salt heat storage device 2 solidifies, the built-in heater 5 can be started to heat so that the molten salt in the single-tank molten salt heat storage device 2 is completely changed from solid to molten state. The molten salt at the bottom of the single-tank molten salt heat storage device 2 is recycled back to the top of the single-tank molten salt heat storage device 2 through the primary heat exchanger 10. At the same time, the desalted water in the deaerator 12 is heated through the primary heat exchanger 10 and then transported to the heat exchange steam coil of the modular molten salt heat storage device 4 to exchange heat with the molten salt and the solid heat storage medium, and the high-temperature steam after heat exchange is transported back to the deaerator 12. When the molten salt in the modular molten salt heat storage device 4 changes from solid to molten state, the system resumes operation. That is, the melting of the solidified molten salt in the modular heat storage device 4 and the single-tank molten salt heat storage device 2 is achieved through the coordinated adjustment of the built-in heater 5 and the external heater 8, thereby improving the flexibility of the modular molten salt heat storage device in situations where there is no stable heat source supply. At the same time, through the clever cooperation of the deaerator 12, the first-stage heat exchanger 10, etc., the energy utilization efficiency of the modular molten salt heat storage device is greatly improved.

[0058] Example 2

[0059] See also Figure 1 The present invention provides a system for improving the utilization efficiency and reliability of molten salt heat storage energy, comprising a single-tank molten salt heat storage device 2, wherein the single-tank molten salt heat storage device 2 is provided with a built-in heater 5 for melting the solidified molten salt in the single-tank molten salt heat storage device 2; the molten salt output end of the single-tank molten salt heat storage device 2 is connected in sequence to a molten salt circulation pump 7, a primary heat exchanger 10, an external heater 8 and a modular molten salt heat storage device 4, and the molten salt output end of the modular molten salt heat storage device 4 is connected to the first molten salt input end at the top of the single-tank molten salt heat storage device 2; preferably, the molten salt circulation pump 7 is a variable frequency pump.

[0060] The molten salt output end of the primary heat exchanger 10 is also connected to the second molten salt input end of the single-tank molten salt heat storage device 2; the water input end of the primary heat exchanger 10 is connected to the deaerator 12, and a water supply pump 1 is arranged between the deaerator 12 and the primary heat exchanger 10. The water output end of the primary heat exchanger 10 is connected to the heat exchange steam coil inside the modular molten salt heat storage device 4, and the outlet steam of the heat exchange steam coil inside the modular molten salt heat storage device 4 is connected to the user and the steam input end of the deaerator 12; preferably, the water supply pump 1 is a variable frequency pump.

[0061] Example 3

[0062] See also Figure 1The present invention provides a system for improving the utilization efficiency and reliability of molten salt heat storage energy, comprising a single-tank molten salt heat storage device 2, wherein the single-tank molten salt heat storage device 2 is provided with a built-in heater 5 for melting the solidified molten salt in the single-tank molten salt heat storage device 2; the molten salt output end of the single-tank molten salt heat storage device 2 is connected in sequence to a molten salt circulation pump 7, a primary heat exchanger 10, an external heater 8 and a modular molten salt heat storage device 4, and the molten salt output end of the modular molten salt heat storage device 4 is connected to the first molten salt input end at the top of the single-tank molten salt heat storage device 2; a molten salt heating valve 14 is provided between the molten salt output end of the primary heat exchanger 10 and the molten salt input end of the external heater 8; preferably, the molten salt circulation pump 7 is a variable frequency pump.

[0063] The molten salt output end of the primary heat exchanger 10 is also connected to the second molten salt input end of the single-tank molten salt heat storage device 2, and a molten salt recirculation valve 13 is provided between the molten salt output end of the primary heat exchanger 10 and the second molten salt input end of the single-tank molten salt heat storage device 2; the water input end of the primary heat exchanger 10 is connected to the deaerator 12, and a water supply pump 1 is provided between the deaerator 12 and the primary heat exchanger 10. The water output end of the primary heat exchanger 10 is connected to the heat exchange steam coil inside the modular molten salt heat storage device 4, and the outlet steam of the heat exchange steam coil inside the modular molten salt heat storage device 4 is connected to the user and the steam input end of the deaerator 12; a molten salt heat storage heating steam heating return steam valve 3 is provided between the internal heater steam output end of the modular molten salt heat storage device 4 and the steam input end of the deaerator 12; a molten salt heat storage device heating valve 11 is provided on the external steam supply pipeline connecting the built-in heater steam output end of the modular molten salt heat storage device 4 to the user; preferably, the water supply pump 1 is a variable frequency pump.

[0064] The modular molten salt heat storage device 4 is arranged on the top of the single-tank molten salt heat storage device 2 through the device connecting pipe 6, and includes a plurality of modular molten salt heat storage units with heat exchangers arranged inside in series, and adjacent modular molten salt heat storage units are connected by module connecting pipes 9.

[0065] When the molten salt solidifies, the built-in heater 5 is started first. When the molten salt in the single-tank molten salt heat storage device 2 is completely changed from solid to molten, the molten salt circulation pump 7 is started to extract the molten salt from the bottom of the single-tank molten salt heat storage device 2, pass through the primary heat exchanger 10, and then pass through the molten salt recirculation valve 13 to return to the top of the single-tank molten salt heat storage device 2. At the same time, the water supply pump 1 is started to heat the desalted water in the deaerator through the primary heat exchanger 10, and then enter the heat exchange steam coil of the modular molten salt heat storage device 4 to exchange heat with the molten salt and the solid heat storage medium. The steam after heat exchange passes through the molten salt heat storage steam heating return valve 3 and returns to the deaerator 12. When the molten salt in the modular molten salt heat storage device 4 is changed from solid to molten, the system resumes operation.

[0066] When the system needs to store heat, the molten salt in the single-tank molten salt heat storage device 2 and the modular molten salt heat storage device 4 is all in a molten state. The molten salt circulation pump 7 is started to extract the molten salt at the bottom of the single-tank molten salt heat storage device 2 through the first-stage heat exchanger 10, enters the sleeve of the external electric heater 8, and finally returns to the molten salt heat storage module inlet 9. The molten salt overflows step by step through the module connecting pipe 15, and finally returns to the top of the single-tank molten salt heat storage device 2 through the device connecting pipe 16. The built-in electric heater 5 is used to adjust the molten salt temperature at the inlet of the external electric heater 8, and the molten salt circulation pump 7 uses a variable frequency pump to adjust the outlet temperature of the external electric heater 8.

[0067] When the system releases heat, the water feed pump 1 extracts the high-temperature desalted water in the deaerator 12, passes through the primary heat exchanger 10 and enters the heat exchange steam coil in the modular molten salt heat storage device 4. One path from the modular molten salt heat storage device 4 is to produce steam and send it to the user through the molten salt heat storage device air supply valve 11. Another path from the modular molten salt heat storage device 4 is to produce steam and send it to the deaerator 12 to heat the desalted water; the molten salt circulation pump 7 extracts the molten salt at the bottom of the single-tank molten salt heat storage device 2 and enters the primary heat exchanger 10 for heat exchange The molten salt outlet of the primary heat exchanger 10 is divided into two paths. One path passes through the molten salt recirculation valve 13 and returns to the top of the single-tank molten salt heat storage device 2. The other path passes through the molten salt heating valve 14 and enters the cylinder of the external electric heater 8, and finally returns to the top of the modular molten salt heat storage device 4 and overflows step by step to the top of the single-tank molten salt heat storage device 2. The molten salt circulation pump 7 uses a variable frequency pump to adjust the water side liquid level of the outlet of the primary heat exchanger 10, and the opening of the molten salt recirculation valve 13 adjusts the steam temperature at the outlet of the modular molten salt heat storage device 4.

[0068] Example 4

[0069] See also Figure 2 A method for improving the efficiency and reliability of molten salt thermal storage energy utilization using the above system comprises:

[0070] When storing heat:

[0071] S1: The molten salt in the single-tank molten salt heat storage device 2 is transported to the external heater 8 through the primary heat exchanger 10 for heating and converted into high-temperature molten salt;

[0072] S2: The high-temperature molten salt is transported to the modular molten salt heat storage device 4 for heat storage, and overflows into the single-tank molten salt heat storage device 2 to complete the heat storage process;

[0073] When releasing heat:

[0074] S1: transporting the high-temperature molten salt stored in the single-tank molten salt heat storage device 2 to the primary heat exchanger 10 for heat exchange;

[0075] S2: After heat exchange, a portion of the molten salt is heated by the external heater 8 and then transported to the modular molten salt heat storage device 4, and overflows into the single-tank molten salt heat storage device 2, and the other portion of the molten salt is directly transported back to the single-tank molten salt heat storage device 2;

[0076] S3: transporting the high-temperature desalted water in the deaerator 12 to the primary heat exchanger 10 for heat exchange with the molten salt entering the primary heat exchanger 10;

[0077] S4: transporting the high-temperature desalted water after heat exchange to the heat exchange steam coil in the modular molten salt heat storage device 4, and producing high-temperature steam using the heat stored in the modular molten salt heat storage device 4;

[0078] S5: A portion of the high-temperature steam is transported to the deaerator 12 to heat the desalted water, and the other portion of the steam is transported to the user for heating, completing the heat release process.

[0079] This method has high energy utilization rate, does not require an external steam heat source, is simple to operate and has good flexibility.

[0080] In summary, the present invention provides a system and method for improving the energy utilization efficiency and reliability of molten salt heat storage. By combining internal and external heaters, a molten salt solidification recovery method without an external steam heat source is realized, which can effectively avoid the safety hazards and low heat storage efficiency caused by molten salt solidification. Compared with the external steam source method, it has better flexibility, and through the clever combination of the single-tank molten salt heat storage device 2 and the modular molten salt heat storage device 4, the energy utilization efficiency is further improved.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and replacements, and these modifications and replacements are also within the scope of protection covered by the claims.

Claims

1. A system for improving the efficiency and reliability of molten salt thermal energy storage, characterized in that: It comprises a single-tank molten salt heat storage device (2), a modular molten salt heat storage device (4), an external heater (8), a primary heat exchanger (10) and a deaerator (12); The single-tank molten salt heat storage device (2) is provided with a built-in heater (5) for melting the solidified molten salt in the single-tank molten salt heat storage device (2); the molten salt output end of the single-tank molten salt heat storage device (2) is connected in sequence to a primary heat exchanger (10), an external heater (8) and a modular molten salt heat storage device (4); The molten salt output end of the modular molten salt heat storage device (4) is connected to the first molten salt input end of the single-tank molten salt heat storage device (2); The high-temperature desalted water output end of the deaerator (12) is connected in sequence to the primary heat exchanger (10) and the built-in heater of the modular molten salt heat storage device (4), and the steam output end of the built-in heater of the modular molten salt heat storage device (4) is connected to the steam input end of the deaerator (12) and the user; The molten salt output end of the primary heat exchanger (10) is also connected to the second molten salt input end of the single-tank molten salt heat storage device (2).

2. The system for improving the efficiency and reliability of molten salt thermal storage energy utilization according to claim 1 is characterized in that: A molten salt circulation pump (7) is provided between the molten salt output end of the single-tank molten salt heat storage device (2) and the molten salt input end of the primary heat exchanger (10), and the molten salt circulation pump (7) is a variable frequency pump.

3. The system for improving the efficiency and reliability of molten salt thermal storage energy utilization according to claim 1 is characterized in that: A water feed pump (1) is provided between the high-temperature desalted water output end of the deaerator (12) and the water input end of the primary heat exchanger (10), and the water feed pump (1) is a variable frequency pump.

4. The system for improving the efficiency and reliability of molten salt thermal energy storage according to claim 1 is characterized in that: A molten salt recirculation valve (13) is provided between the molten salt output end of the primary heat exchanger (10) and the second molten salt input end of the single-tank molten salt heat storage device (2).

5. The system for improving the efficiency and reliability of molten salt thermal energy storage according to claim 1 is characterized in that: A molten salt heating valve (14) is provided between the molten salt output end of the primary heat exchanger (10) and the molten salt input end of the external heater (8).

6. The system for improving the efficiency and reliability of molten salt thermal energy storage according to claim 1, characterized in that: A molten salt heat storage heating steam heating return valve (3) is provided between the steam output end of the built-in heater of the modular molten salt heat storage device (4) and the steam input end of the deaerator (12).

7. The system for improving the efficiency and reliability of molten salt thermal storage energy utilization according to claim 1, characterized in that: A molten salt heat storage device heating valve (11) is provided on an external steam supply pipeline connected to a user at the steam output end of the built-in heater of the modular molten salt heat storage device (4).

8. The system for improving the efficiency and reliability of molten salt thermal storage energy utilization according to any one of claims 1 to 7, characterized in that: The modular molten salt heat storage device (4) comprises a plurality of modular molten salt heat storage units with built-in heaters connected in series, and adjacent modular molten salt heat storage units are connected via module connecting pipes (9).

9. The system for improving the efficiency and reliability of molten salt thermal storage energy utilization according to any one of claims 1 to 7, characterized in that: The molten salt output end of the modular molten salt heat storage device (4) is connected to the first molten salt input end of the single-tank molten salt heat storage device (2) via a device connecting pipe (6).

10. A method for improving the efficiency and reliability of molten salt thermal storage energy utilization using the system according to any one of claims 1 to 9, characterized in that: include: When storing heat: The molten salt in the single-tank molten salt heat storage device (2) is transported to the external heater (8) through the primary heat exchanger (10) for heating and converted into high-temperature molten salt; The high-temperature molten salt is transported to the modular molten salt heat storage device (4) for heat storage, and overflows into the single-tank molten salt heat storage device (2) to complete the heat storage process; When releasing heat: The high-temperature molten salt stored in the single-tank molten salt heat storage device (2) is transported to the primary heat exchanger (10) for heat exchange; A portion of the molten salt after heat exchange is heated by an external heater (8), and then transported to a modular molten salt heat storage device (4), and overflows into a single-tank molten salt heat storage device (2), and another portion of the molten salt is directly transported back to the single-tank molten salt heat storage device (2); The high-temperature desalted water in the deaerator (12) is transported to the primary heat exchanger (10) for heat exchange with the molten salt entering the primary heat exchanger (10); The high-temperature desalted water after heat exchange is transported to the heat exchange steam coil in the modular molten salt heat storage device (4), and high-temperature steam is produced using the heat stored in the modular molten salt heat storage device (4); A portion of the high-temperature steam is transported to the deaerator (12) to heat the desalted water, and the other portion of the steam is transported to the user for heating, thereby completing the heat release process.

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