Fused salt heat storage peak shaving system

Abstract

The invention relates to a fused salt heat storage peak shaving system which comprises a low-temperature fused salt tank, a high-temperature fused salt tank, a control module, a mixed heat storage module and a multi-stage heat release module, when it is judged that a power consumption trough period is reached, the control module controls the mixed heat storage module to start and operate, and energy of a coal power unit is used for storing heat. The low-temperature molten salt in the low-temperature molten salt tank is heated into the high-temperature molten salt on the heat storage circulating pipeline in at least one heating mode and then stored in the high-temperature molten salt tank, the limitation of a single heating mode is broken through, multiple energy sources are flexibly called, and the operation cost in the heat storage process is reduced. And when it is judged that the power utilization peak period is reached, the multi-stage heat release module is controlled to start and operate, heat of the high-temperature molten salt in the high-temperature molten salt tank is released to the coal power unit in a graded mode on the heat release circulation pipeline, and obtained low-temperature molten salt is stored in the low-temperature molten salt tank. The cascade heat release design can reduce the heat exchange temperature difference of each stage, greatly reduce irreversible loss, improve the heat recovery efficiency, reduce the steam extraction amount of each stage of the steam turbine, and remarkably improve the power generation capacity of the unit.

Description

Technical Field

[0001] This application relates to the field of coal-fired power generation technology, and in particular to a molten salt thermal storage peak-shaving system. Background Technology

[0002] The strong intermittency, volatility, and randomness of renewable energy generation such as wind and solar power pose a severe challenge to the safe and stable operation of the power grid. Against this backdrop, fully exploring and enhancing the deep peak-shaving capacity of coal-fired power units has become a key support for balancing renewable energy fluctuations and ensuring a reliable power supply.

[0003] Molten salt thermal energy storage technology, as an efficient energy time-shifting method, can achieve decoupled operation of power generation and heating by coupling with coal-fired power units. It can store the surplus energy of the unit during off-peak hours and release it during peak electricity demand or when the output of new energy sources is insufficient, thereby realizing the time-scheduled matching of power generation and load and significantly enhancing the unit's regulation capability.

[0004] However, the molten salt thermal storage peak-shaving system currently used in coal-fired power units has technical problems that affect the overall performance during both the thermal storage and heat release processes, and cannot meet the higher requirements of the new power system for flexible peak-shaving of coal-fired power units. Summary of the Invention

[0005] Therefore, it is necessary to provide a molten salt thermal storage peak-shaving system to address the technical problems that exist in the molten salt thermal storage peak-shaving system applied to coal-fired power units during both the thermal storage and heat release processes, which affect the overall performance and fail to meet the higher requirements of the new power system for flexible peak-shaving of coal-fired power units.

[0006] A molten salt thermal storage peak-shaving system includes a low-temperature molten salt tank, a high-temperature molten salt tank and a control module, as well as a hybrid thermal storage module and a multi-stage heat release module connected to the control module;

[0007] The outlet of the low-temperature molten salt tank is connected to the inlet of the high-temperature molten salt tank through a heat storage circulation pipeline, and the outlet of the high-temperature molten salt tank is connected to the inlet of the low-temperature molten salt tank through a heat release circulation pipeline. The mixed heat storage module is installed in the heat storage circulation pipeline, and the multi-stage heat release module is installed in the heat release circulation pipeline. The mixed heat storage module and the multi-stage heat release module are also connected to a coal-fired power unit.

[0008] When the control module determines that the electricity consumption period has reached a low point, it controls the hybrid thermal storage module to start operation and use the energy of the coal-fired power unit to heat the low-temperature molten salt in the low-temperature molten salt tank into high-temperature molten salt in the thermal storage circulation pipeline through at least one heating method, and then store it in the high-temperature molten salt tank.

[0009] When the control module determines that the peak electricity consumption period has been reached, it controls the multi-stage heat release module to start operation. In the heat release circulation pipeline, the heat of the high-temperature molten salt in the high-temperature molten salt tank is released to the coal-fired power unit in stages, and the resulting low-temperature molten salt is stored in the low-temperature molten salt tank.

[0010] In one embodiment, the multi-stage heat release module includes a series of multi-stage molten salt-feedwater heat exchangers. The molten salt side of each stage of the molten salt-feedwater heat exchanger is connected in series through the heat release circulation pipeline. The feedwater side of each stage of the molten salt-feedwater heat exchanger is connected through pipelines to one or more of the multi-stage high-pressure heating components, deaerator, and multi-stage low-pressure heating components of the coal-fired power unit.

[0011] In one embodiment, the multi-stage heat release module includes a first-stage molten salt-feedwater heat exchanger, a second-stage molten salt-feedwater heat exchanger, a third-stage molten salt-feedwater heat exchanger, and a fourth-stage molten salt-feedwater heat exchanger.

[0012] The heat release circulation pipeline is connected in series with the first-stage molten salt-feed water heat exchanger, the second-stage molten salt-feed water heat exchanger, the third-stage molten salt-feed water heat exchanger, and the molten salt side of the fourth-stage molten salt-feed water heat exchanger.

[0013] The feedwater sides of the first-stage molten salt-feedwater heat exchanger and the second-stage molten salt-feedwater heat exchanger are connected to the condensate pipeline of the multi-stage high-pressure heating assembly via pipelines. The feedwater side of the third-stage molten salt-feedwater heat exchanger is connected to the condensate pipeline of the deaerator via pipelines. The feedwater side of the fourth-stage molten salt-feedwater heat exchanger is connected to the condensate pipeline of the multi-stage low-pressure heating assembly via pipelines.

[0014] In one embodiment, the hybrid thermal storage module includes a steam extraction heating unit and an electric heating unit, both of which are disposed in the thermal storage circulation pipeline;

[0015] The steam extraction heating unit is connected to the coal-fired power unit through a steam extraction pipeline, so as to use the heat of the steam generated by the coal-fired power unit to steam heat the low-temperature molten salt in the low-temperature molten salt tank.

[0016] The electric heating unit is connected to the coal-fired power unit via a power supply line to use the electrical energy generated by the coal-fired power unit to electrically heat the low-temperature molten salt in the low-temperature molten salt tank.

[0017] In one embodiment, the steam extraction heating unit and the electric heating unit are sequentially arranged in the heat storage circulation pipeline;

[0018] The molten salt thermal storage peak shaving system further includes: a monitoring module connected to the control module, wherein the monitoring module is installed in the thermal storage circulation pipeline;

[0019] The monitoring module is used to collect the first molten salt temperature, which is the molten salt temperature in the heat storage circulation pipeline behind the steam extraction heating unit.

[0020] When the control module determines that the electricity consumption period is low, it controls the steam extraction heating unit to start operating. When it determines that the heat storage is incomplete based on the first molten salt temperature, it controls the electric heating unit to start operating.

[0021] In one embodiment, the extraction steam heating unit includes a steam-molten salt heat exchanger and an extraction steam flow regulating valve;

[0022] The molten salt pipeline of the steam-molten salt heat exchanger is connected in series with the heat storage circulation pipeline. The inlet of the steam pipeline of the steam-molten salt heat exchanger is connected to the reheat steam outlet of the boiler of the coal-fired power unit through the steam extraction pipeline. The outlet of the steam pipeline is connected to the condenser of the coal-fired power unit through the steam exhaust pipeline.

[0023] The steam extraction flow regulating valve is installed in the steam extraction pipeline and is connected to the control module.

[0024] In one embodiment, the electric heating unit includes an electric heater connected in series with the heat storage circulation pipeline, the power supply terminal of the electric heater is connected to the coal-fired power unit, and the power adjustment terminal of the electric heater is connected to the control module.

[0025] In one embodiment,

[0026] Upon receiving a low-peak scheduling command and / or a low-load command, the control module determines that the electricity consumption off-peak period has been reached.

[0027] Upon receiving peak scheduling instructions and / or high load instructions, the control module determines that the peak electricity consumption period has been reached.

[0028] In one embodiment, the system further includes a first molten salt pump and a second molten salt pump, wherein the first molten salt pump is located on the heat storage circulation pipeline near the outlet of the low-temperature molten salt tank, and the second molten salt pump is located on the heat release circulation pipeline near the outlet of the high-temperature molten salt tank.

[0029] In one embodiment, it further includes: a monitoring module connected to the control module, the monitoring module including a temperature acquisition unit, a pressure acquisition unit and a flow acquisition unit;

[0030] The temperature acquisition unit is installed in the heat storage circulation pipeline, the heat release circulation pipeline, the hybrid heat storage module, and the multi-stage heat release module to acquire temperature data; the pressure acquisition unit is installed in the heat storage circulation pipeline, the heat release circulation pipeline, the hybrid heat storage module, and the multi-stage heat release module to acquire pressure data; the flow acquisition unit is installed in the heat storage circulation pipeline, the heat release circulation pipeline, the hybrid heat storage module, and the multi-stage heat release module to acquire flow data.

[0031] The control module is used to determine, based on the temperature data, pressure data, and flow data, that there is an abnormality in the thermal storage operation, and output a shutdown command to the first molten salt pump and the mixed thermal storage module to control the cessation of thermal storage operation; and to determine, based on the temperature data, pressure data, and flow data, that there is an abnormality in the heat release operation, and output a shutdown command to the second molten salt pump and the multi-stage heat release module to control the cessation of heat release operation.

[0032] The aforementioned molten salt thermal storage peak-shaving system includes a low-temperature molten salt tank, a high-temperature molten salt tank, a control module, a hybrid thermal storage module, and a multi-stage heat release module. The low-temperature molten salt tank is connected to the high-temperature molten salt tank via a thermal storage circulation pipeline equipped with the hybrid thermal storage module. The high-temperature molten salt tank is connected to the low-temperature molten salt tank via a heat release circulation pipeline equipped with the multi-stage heat release module. When an off-peak electricity demand is detected, the control module activates the hybrid thermal storage module. Utilizing the energy of the coal-fired power unit, the low-temperature molten salt in the low-temperature molten salt tank is heated to high-temperature molten salt via at least one heating method in the thermal storage circulation pipeline and then stored in the high-temperature molten salt tank. By overcoming the limitations of a single heating method and flexibly utilizing multiple energy sources (steam extraction, electricity, etc.), the system achieves an optimal balance between low cost and high flexibility, significantly reducing the total operating cost of the thermal storage process. Conversely, when a peak electricity demand is detected, the multi-stage heat release module is activated. In the heat release circulation pipeline, the heat from the high-temperature molten salt in the high-temperature molten salt tank is released in stages to the coal-fired power unit, resulting in low-temperature molten salt stored in the low-temperature molten salt tank. Through a cascaded heat release design, the heat of molten salt is transferred step by step to the feedwater of the coal-fired power unit or used to generate steam, reducing the temperature difference of heat exchange at each stage, significantly reducing irreversible heat loss, improving heat recovery efficiency, reducing the amount of steam extracted at each stage of the turbine, and significantly improving the power generation capacity of the unit. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the system block diagram of the molten salt thermal storage peak shaving system in one embodiment;

[0035] Figure 2 This is a schematic diagram of the thermal storage process of a molten salt thermal storage peak-shaving system in one embodiment;

[0036] Figure 3 This is a schematic diagram of the heat release process of a molten salt thermal storage peak-shaving system in one embodiment. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. The accompanying drawings illustrate embodiments of this application; however, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of this application more thorough and complete. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0039] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0040] It is understandable that "at least one" refers to one or more, and "multiple" refers to two or more. "At least a part of an element" refers to part or all of an element.

[0041] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0043] In one exemplary embodiment, such as Figure 1 As shown, a molten salt thermal storage peak-shaving system is provided, including a low-temperature molten salt tank 110, a high-temperature molten salt tank 120, and a control module 130, as well as a hybrid thermal storage module 140 and a multi-stage heat release module 150 connected to the control module 130. The outlet of the low-temperature molten salt tank 110 is connected to the inlet of the high-temperature molten salt tank 120 through a thermal storage circulation pipeline A, and the outlet of the high-temperature molten salt tank 120 is connected to the inlet of the low-temperature molten salt tank 110 through a heat release circulation pipeline B. The hybrid thermal storage module 140 is disposed in the thermal storage circulation pipeline A, and the multi-stage heat release module 150 is disposed in the heat release circulation pipeline B. The hybrid thermal storage module 140 and the multi-stage heat release module 150 are connected to each other. 0 is also connected to the coal-fired power unit; when the control module 130 determines that the power consumption period has reached its off-peak period, it controls the mixed heat storage module 140 to start operation, using the energy of the coal-fired power unit to heat the low-temperature molten salt in the low-temperature molten salt tank 110 into high-temperature molten salt through at least one heating method on the heat storage circulation pipeline A, and then stores it in the high-temperature molten salt tank 120; when the control module 130 determines that the power consumption period has reached its peak period, it controls the multi-stage heat release module 150 to start operation, and releases the heat of the high-temperature molten salt in the high-temperature molten salt tank 120 to the coal-fired power unit in stages on the heat release circulation pipeline B, so that the low-temperature molten salt is stored in the low-temperature molten salt tank 110.

[0044] Specifically, the low-temperature molten salt tank 110 is a container for storing low-temperature solid or liquid molten salt, and the temperature range of the molten salt stored inside can be around 200℃. The high-temperature molten salt tank 120 is a container for storing high-temperature molten salt heated by the mixing heat storage module 140, and the molten salt temperature can reach 450℃–565℃, close to or reaching the main steam temperature of the coal-fired power unit. The low-temperature molten salt tank 110 and the high-temperature molten salt tank 120 can be connected respectively through a heat storage circulation pipeline A and a heat release circulation pipeline B. The low-temperature molten salt tank 110 can serve as the starting point of the heat storage circulation pipeline A and the ending point of the heat release circulation pipeline B, while the high-temperature molten salt tank 120, conversely, serves as the starting point of the heat release circulation pipeline B and the ending point of the heat storage circulation pipeline A. For example, the volume of the low-temperature molten salt tank 110 and the high-temperature molten salt tank 120 is not limited and can be designed according to a heat storage power of 90~100MW.

[0045] The heat storage circulation pipeline A forms a closed loop path where molten salt flows out of the low-temperature molten salt tank 110, is heated by the mixing heat storage module 140, and finally flows into the high-temperature molten salt tank 120. The heat release circulation pipeline B forms a closed loop path where molten salt flows out of the high-temperature molten salt tank 120, releases heat through the multi-stage heat release module 150 to feed the coal-fired power unit, and the cooled molten salt flows back to the low-temperature molten salt tank 110.

[0046] For example, the cryogenic molten salt tank 110 and the high-temperature molten salt tank 120 can be designed for heat preservation, anti-condensation, corrosion prevention, and sealing. In particular, the high-temperature molten salt tank 120 needs to have a higher level of heat preservation performance and withstand high temperature and high pressure sealing requirements. Similarly, the heat storage circulation pipeline A and the heat release circulation pipeline B also need to be made of materials resistant to high temperature molten salt corrosion (such as stainless steel 316L, metal alloys, etc.), and need to be corrosion resistant, and can optionally be equipped with necessary fluid control and monitoring equipment.

[0047] In one exemplary embodiment, reference continues to... Figure 1 The molten salt thermal storage peak shaving system may also include a first molten salt pump 111 and a second molten salt pump 121. The first molten salt pump 111 is located on the thermal storage circulation pipeline A near the outlet of the low-temperature molten salt tank 110, and the second molten salt pump 121 is located on the heat release circulation pipeline B near the outlet of the high-temperature molten salt tank 120.

[0048] Specifically, the first molten salt pump 111 is the driving core of the heat storage cycle. It is fixedly installed on the heat storage cycle pipeline A and adjacent to the outlet of the low-temperature molten salt tank 110. This ensures that the molten salt flowing out of the low-temperature molten salt tank 110 can be immediately pressurized and transported by the pump, avoiding the risk of flow stagnation or solidification at the tank outlet. The second molten salt pump 121 is the driving core of the heat release cycle. It is fixedly installed on the heat release cycle pipeline B and adjacent to the outlet of the high-temperature molten salt tank 120. This allows the high-temperature molten salt to be pressurized by the pump immediately after leaving the high-temperature molten salt tank 120, maintaining the forced flow heat exchange efficiency of the high-temperature molten salt in the subsequent multi-stage heat release module 150.

[0049] It is understood that the selection of pump components for the first molten salt pump 111 and the second molten salt pump 121 is not unique and can be selected according to actual technical requirements. For example, in this embodiment, the first molten salt pump 111 can be a high-temperature corrosion-resistant centrifugal pump, and the second molten salt pump 121 can be a high-temperature long-shaft molten salt pump.

[0050] In one example, the type of molten salt chosen in the system is not unique and can be selected based on actual technical requirements. Conventional binary nitrates can be used as the molten salt, with an operating temperature range of ~220°C-565°C and low cost. Alternatively, ternary nitrates or additives can be used to improve high-temperature stability and lower the melting point. For scenarios requiring even higher temperatures, chlorides or carbonates can also be considered as molten salts.

[0051] Furthermore, the hybrid thermal storage module 140 is a module for heating low-temperature molten salt. During the thermal storage process, it utilizes one or more energy sources from a coal-fired power unit to heat the low-temperature molten salt flowing through the thermal storage circulation pipeline A into high-temperature molten salt. The term "hybrid" can be defined as supporting the coordinated or independent operation of at least two different heating methods due to differences in energy sources or principles.

[0052] For example, the hybrid thermal storage module 140 can employ multiple heating methods, such as steam extraction heating, electric heating, and flue gas waste heat heating, working in tandem. Specifically, it can intelligently allocate the load ratio of each heating method based on real-time energy costs (electricity price), coal-fired power unit load, steam parameters, target thermal storage temperature / power, etc., to achieve heating during the thermal storage process. The steam extraction heating method involves extracting medium- or low-pressure steam from the boiler or turbine of the coal-fired power unit (e.g., the steam extraction port) to indirectly exchange heat with the molten salt flowing through the thermal storage circulation pipeline A. The electric heating method utilizes electrical energy (which can come from the power generated by the coal-fired power unit or off-peak electricity from the grid) to drive electric heaters to heat the molten salt. Furthermore, the electric heating method can employ electric heaters of different power levels or different locations to achieve multi-stage electric heating. The flue gas waste heat heating method utilizes the waste heat from the medium- and low-temperature flue gas discharged from the boiler of the coal-fired power unit to preheat or supplement the heating of the molten salt.

[0053] Furthermore, the multi-stage heat release module 150 is a module for multi-stage heat release from high-temperature molten salt. During the heat release process, it efficiently transfers the heat from the high-temperature molten salt flowing through the heat release circulation pipeline B to multiple heat exchange points (usually feedwater or steam) in the coal-fired power unit in stages and according to grade, to drive the steam turbine for power generation. The term "multi-stage" can refer to a heat release loop containing two or more stages connected in series or parallel. Each stage recovers heat from the molten salt in different temperature ranges and is coupled to heat exchange points in the coal-fired power unit with different parameter requirements.

[0054] For example, the multi-stage heat release module 150 can heat the feedwater of a coal-fired power unit through two-stage series heat release circuits. In the first-stage heat release circuit, high-temperature molten salt (e.g., 550°C) heats the high-pressure feedwater to a higher temperature (e.g., near saturation temperature), replacing part or all of the high-pressure heater. In the second-stage heat release circuit, the molten salt, after being cooled in the first stage, continues to heat the lower-pressure feedwater (e.g., deaerator outlet water), replacing part of the low-pressure heater.

[0055] For example, the multi-stage heat release module 150 can also heat the steam and feedwater in a coal-fired power unit through two parallel heat release circuits. In the first-stage heat release circuit, high-temperature molten salt (e.g., 550°C) evaporates to generate medium- or low-pressure steam, which is directly injected into the medium / low-pressure cylinder of the turbine to perform work or for heating. In the second-stage heat release circuit, the molten salt, cooled in the first stage, continues to preheat the boiler feedwater.

[0056] To control the heat storage and release processes, a control module 130 is also provided in the molten salt thermal storage peak-shaving system. Exemplarily, the control module 130 can be a controller installed within the molten salt thermal storage peak-shaving system, or it can be implemented using an existing controller from a coal-fired power unit. The specific controller type is not limited; it can be an FPGA (Field Programmable Gate Array) chip, a Central Processing Unit (CPU), a Microcontroller Unit (MCU), or a Digital Signal Processor (DSP), etc. In this embodiment, the control module 130 is implemented using a PLC (Programmable Logic Controller).

[0057] Specifically, the control module 130 can receive sensor signals from the molten salt thermal storage peak-shaving system and external signals to determine whether the current period is a low-demand period or a high-demand period, thereby realizing the switching control of the thermal storage process / heat release process. The sensor signals from the molten salt thermal storage peak-shaving system can include molten salt temperature / pressure / flow data at various locations within the system, or pump parameters or valve position parameters at various locations within the system. External signals can include grid dispatch instructions and real-time electricity price information issued by the power grid, as well as steam parameters, energy parameters, and load instructions from coal-fired power units.

[0058] Furthermore, when the control module 130 determines that the power consumption period is at its lowest, it controls the mixed thermal storage module 140 to start operation. Utilizing the energy of the coal-fired power unit, the low-temperature molten salt in the low-temperature molten salt tank 110 is heated to high-temperature molten salt via at least one heating method on the thermal storage circulation pipeline A, and then stored in the high-temperature molten salt tank 120. The start-up of the mixed thermal storage module 140 can be achieved by dynamically adjusting the operating status and output ratio of each heating unit (such as the opening degree of the extraction steam valve and the power of the electric heater) within the mixed thermal storage module 140, based on the activation of the first molten salt pump 111 on the thermal storage circulation pipeline A. This ensures that the low-temperature molten salt is safely and efficiently heated to the set high temperature, resulting in high-temperature molten salt, which is then stored in the high-temperature molten salt tank 120.

[0059] When the control module 130 determines that the peak electricity demand period has arrived, it controls the multi-stage heat release module 150 to start operating. On the heat release circulation pipeline B, the heat from the high-temperature molten salt in the high-temperature molten salt tank 120 is released in stages to the coal-fired power unit, resulting in low-temperature molten salt stored in the low-temperature molten salt tank 110. The control of the multi-stage heat release module 150 can be achieved by starting the second molten salt pump 121 on the heat release circulation pipeline B, coordinating the molten salt flow rate and valve opening of each stage of the heat release circuit, and matching it with the interface parameters on the coal-fired power unit side (such as feedwater flow distribution and steam injection point pressure) to ensure that the heat from the high-temperature molten salt is extracted efficiently and in multiple stages for power generation, while maintaining stable system parameters.

[0060] The aforementioned molten salt thermal storage peak-shaving system includes a low-temperature molten salt tank, a high-temperature molten salt tank, a control module, a hybrid thermal storage module, and a multi-stage heat release module. The low-temperature molten salt tank is connected to the high-temperature molten salt tank via a thermal storage circulation pipeline equipped with the hybrid thermal storage module. The high-temperature molten salt tank is connected to the low-temperature molten salt tank via a heat release circulation pipeline equipped with the multi-stage heat release module. When an off-peak electricity demand is detected, the control module activates the hybrid thermal storage module. Utilizing the energy of the coal-fired power unit, the low-temperature molten salt in the low-temperature molten salt tank is heated to high-temperature molten salt via at least one heating method in the thermal storage circulation pipeline and then stored in the high-temperature molten salt tank. By overcoming the limitations of a single heating method and flexibly utilizing multiple energy sources (steam extraction, electricity, etc.), the system achieves an optimal balance between low cost and high flexibility, significantly reducing the total operating cost of the thermal storage process. Conversely, when a peak electricity demand is detected, the multi-stage heat release module is activated. In the heat release circulation pipeline, the heat from the high-temperature molten salt in the high-temperature molten salt tank is released in stages to the coal-fired power unit, resulting in low-temperature molten salt stored in the low-temperature molten salt tank. Through a cascaded heat release design, the heat of molten salt is transferred step by step to the feedwater of the coal-fired power unit or used to generate steam, reducing the temperature difference of heat exchange at each stage, significantly reducing irreversible heat loss, improving heat recovery efficiency, reducing the amount of steam extracted at each stage of the turbine, and significantly improving the power generation capacity of the unit.

[0061] In one exemplary embodiment, the multi-stage heat release module includes a series of multi-stage molten salt-feedwater heat exchangers. The molten salt side of each stage of the molten salt-feedwater heat exchanger is connected in series via a heat release circulation pipeline. The feedwater side of each stage of the molten salt-feedwater heat exchanger is connected via a pipeline to one or more of the multi-stage high-pressure heating components, deaerator, and multi-stage low-pressure heating components of the coal-fired power unit.

[0062] Specifically, this embodiment uses a series of multi-stage heat exchangers as the heat release loop for the high-temperature molten salt, forming the core device for the cascaded release of molten salt heat. The multi-stage heat exchanger can be a molten salt-feedwater heat exchanger, i.e., a device used to achieve heat exchange between the molten salt and the feedwater loop of the coal-fired power unit. Its molten salt side is connected in series via heat release circulation pipelines, while the feedwater side can be connected via pipelines to one or more of the multi-stage high-pressure heating components, deaerator, and multi-stage low-pressure heating components of the coal-fired power unit. The specific connected heat exchange devices and their locations can be designed to meet the different temperature ranges of molten salt heat and the different parameter requirements of the coal-fired power unit, achieving temperature matching between the molten salt heat release curve and the feedwater heat absorption curve, thus reducing heat exchange losses.

[0063] It should be noted that the molten salt thermal storage peak-shaving system provided in this application can be applied to various coal-fired power units, as long as the thermal storage part and the thermal release part are connected to the corresponding parts of the coal-fired power unit.

[0064] In one example, refer to Figure 2 This paper provides a schematic diagram of a coal-fired power unit. The coal-fired power unit includes a boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a deaerator 9, a feedwater pump 10, a condensate pump 15, a condenser 16, a multi-stage high-pressure heating assembly, and a multi-stage low-pressure heating assembly. The multi-stage high-pressure heating assembly includes a first high-pressure heater 6, a second high-pressure heater 7, and a third high-pressure heater 8; the multi-stage low-pressure heating assembly includes a first low-pressure heater 11, a second low-pressure heater 12, a third low-pressure heater 3, and a fourth low-pressure heater 14. Correspondingly, the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 are connected in series; the first high-pressure heater 6, the second high-pressure heater 7, and the third high-pressure heater 8 are connected in series; and the first low-pressure heater 11, the second low-pressure heater 12, the third low-pressure heater 3, and the fourth low-pressure heater 14 are connected in series. The boiler 1 is connected to the feedwater pump 10 of the deaerator 9 via the series-connected multi-stage high-pressure heating assembly. The boiler 1 is also connected to the high-pressure cylinder 2 and the intermediate-pressure cylinder 3. High-pressure cylinder 2 is also connected to the first high-pressure heater 6 and the second high-pressure heater 7; intermediate-pressure cylinder 3 is connected to the third high-pressure heater 8 and the deaerator 9; low-pressure cylinder 4 is connected to each low-pressure heater in the multi-stage low-pressure heating assembly; low-pressure cylinder 4 is also connected to the generator 5 and the condenser 16; deaerator 9 is also connected to the first low-pressure heater 11; and condenser 16 is connected to the fourth low-pressure heater 14 via condensate pump 15. It is understood that the specific operating principle of the above-mentioned coal-fired power unit is not detailed here, but can be obtained by referring to what is known in the art.

[0065] In one exemplary embodiment, such as Figure 2As shown, the multi-stage heat release module 150 includes a first-stage molten salt-feedwater heat exchanger 151, a second-stage molten salt-feedwater heat exchanger 152, a third-stage molten salt-feedwater heat exchanger 153, and a fourth-stage molten salt-feedwater heat exchanger 154. The heat release circulation pipeline B is connected in series to the molten salt side of the first-stage molten salt-feed water heat exchanger 151, the second-stage molten salt-feed water heat exchanger 152, the third-stage molten salt-feed water heat exchanger 153, and the fourth-stage molten salt-feed water heat exchanger 154. The feed water side of the first-stage molten salt-feed water heat exchanger 151 and the second-stage molten salt-feed water heat exchanger 152 is connected to the condensate pipeline of the multi-stage high-pressure heating assembly through a pipeline. The feed water side of the third-stage molten salt-feed water heat exchanger 153 is connected to the condensate pipeline of the deaerator 9 through a pipeline. The feed water side of the fourth-stage molten salt-feed water heat exchanger 154 is connected to the condensate pipeline of the multi-stage low-pressure heating assembly through a pipeline.

[0066] Specifically, this embodiment uses a four-stage series heat exchanger structure as a multi-stage heat release module 150 to realize the heat release process of high-temperature molten salt. The heat release circulation pipeline B is sequentially connected in series to the molten salt side of the first-stage molten salt-feedwater heat exchanger 151, the second-stage molten salt-feedwater heat exchanger 152, the third-stage molten salt-feedwater heat exchanger 153, and the fourth-stage molten salt-feedwater heat exchanger 154. The high-temperature molten salt flows sequentially through the four heat exchangers according to the aforementioned series pipeline, forming a path with progressively decreasing temperature. Furthermore, no parallel connections or bypasses are provided between the molten salt flow paths of each stage, ensuring that the heat of the molten salt is fully released according to its grade gradient.

[0067] Furthermore, the molten salt with the highest heat grade is first recovered to the condensate pipeline of the multi-stage high-pressure heating assembly. Specifically, this is achieved through the first-stage molten salt-feedwater heat exchanger 151 and the second-stage molten salt-feedwater heat exchanger 152. The inlet of their molten salt side pipeline is connected to the outlet of the high-temperature molten salt tank 120. After heat exchange with the condensate pipeline of the multi-stage high-pressure heating assembly, the molten salt is output to the next-stage molten salt-feedwater heat exchanger. Their feedwater side pipelines are connected in series in the pipe sections between each stage of the high-pressure heater. For example, the feedwater side pipeline of the first-stage molten salt-feedwater heat exchanger 151 is connected in series in the pipeline between the second high-pressure heater 7 and the first high-pressure heater 6, and the feedwater side pipeline of the second-stage molten salt-feedwater heat exchanger 152 is connected in series in the pipeline between the third high-pressure heater 8 and the second high-pressure heater 7. This can be understood as follows: for molten salt with the highest heat grade, its heat is exchanged to the feedwater pipeline of the high-pressure heater to replace part of the load of the high-pressure heater, heating the high-pressure feedwater to near saturation, allowing more high-temperature steam to enter the turbine to expand and do work, directly improving power generation efficiency.

[0068] Secondly, the molten salt with medium-grade heat is recovered to the deaerator condensate pipeline. This is specifically achieved through the third-stage molten salt-feedwater heat exchanger 153, whose molten salt-side pipeline inlet connects to the molten salt-side pipeline outlet of the second-stage molten salt-feedwater heat exchanger 152, and whose molten salt-side pipeline outlet connects to the next-stage molten salt-feedwater heat exchanger. The feedwater-side pipeline connects to the pipeline section from the deaerator outlet to the high-pressure heater inlet. This can be understood as the molten salt with partially exchanged medium-grade heat being precisely supplied to the deaerator for preheating the deaerator feedwater, replacing the original steam heating, compensating for the steam consumption in the low-pressure cylinder extraction, and reducing exhaust steam losses.

[0069] Finally, the low-grade heat molten salt is recovered to the condensate pipeline of the low-pressure heating assembly. This is specifically achieved through a fourth-stage molten salt-feedwater heat exchanger 154, whose molten salt-side pipeline inlet is connected to the molten salt-side pipeline outlet of the third-stage molten salt-feedwater heat exchanger 153, and whose molten salt-side pipeline outlet is connected to the inlet of the cryogenic molten salt tank 110. The feedwater-side pipeline connects to the pipe section between the low-pressure heaters, for example, it could be the pipeline connecting the first low-pressure heater 11 and the second low-pressure heater 12. This can be understood as preheating the condensate of the low-pressure heaters with low-temperature heat, achieving deep-limit recovery of low-temperature heat, and realizing the value-added utilization of traditional waste energy.

[0070] It should be noted that the feedwater side of each stage of the molten salt-feedwater heat exchanger in the multi-stage heat release module 150 is connected to the main feedwater pipeline of the boiler after the feedwater outlet pipeline merges, so that the heated feedwater enters the boiler to participate in the circulation.

[0071] In this embodiment, by releasing the heat of molten salt in stages according to grade, the average heat exchange temperature difference is significantly reduced, the utilization rate of low-temperature heat is improved, which in turn supports the ultra-low load operation of the unit, reduces irreversible heat loss, and improves heat recovery efficiency.

[0072] In one exemplary embodiment, such as Figure 3 As shown, the hybrid thermal storage module 140 includes a steam extraction heating unit 141 and an electric heating unit 142, both of which are located in the thermal storage circulation pipeline A. The steam extraction heating unit 141 is connected to the coal-fired power unit through a steam extraction pipeline to utilize the heat from the steam generated by the coal-fired power unit to heat the low-temperature molten salt in the low-temperature molten salt tank 110. The electric heating unit 142 is connected to the coal-fired power unit through a power supply line to utilize the electrical energy generated by the coal-fired power unit to heat the low-temperature molten salt in the low-temperature molten salt tank 110.

[0073] Specifically, the hybrid thermal storage module 140 is composed of a steam extraction heating unit 141 and an electric heating unit 142. The steam extraction heating unit 141 and the electric heating unit 142 can be connected in parallel on the thermal storage circulation pipeline A to achieve dual-source coordinated heating of steam thermal energy and electrical energy, while also supporting switching between pure electric heating and pure steam heating modes. Alternatively, the steam extraction heating unit 141 and the electric heating unit 142 can be connected in series on the thermal storage circulation pipeline A to mutually compensate for each other and increase the maximum temperature that the molten salt can be heated to.

[0074] The extraction steam heating unit 141 is connected to the coal-fired power unit via a steam extraction pipeline to utilize the heat of the steam generated by the coal-fired power unit to heat the low-temperature molten salt in the low-temperature molten salt tank 110. Depending on the specific steam temperature, the molten salt is heated from 200°C to 350-400°C. For example, the steam extraction heating unit 141, connected to the coal-fired power unit via a steam extraction pipeline, can be connected to the boiler's extraction port, such as the reheat steam outlet connecting the boiler to the intermediate-pressure cylinder, or the high-pressure heater extraction port connecting the boiler to the high-pressure cylinder.

[0075] In this embodiment, by using a hybrid heating method, the thermal storage process can achieve a 25% deep peak shaving for coal-fired power units, increase the maximum electrical load during the heat release stage, and cover the entire scenario from off-peak to peak electricity consumption.

[0076] In an exemplary embodiment, the steam extraction heating unit includes a steam-molten salt heat exchanger and a steam extraction flow regulating valve; the molten salt pipeline of the steam-molten salt heat exchanger is connected in series with the heat storage circulation pipeline, the inlet of the steam pipeline of the steam-molten salt heat exchanger is connected to the reheat steam outlet of the boiler of the coal-fired power unit through the steam extraction pipeline, and the outlet of the steam pipeline is connected to the condenser of the coal-fired power unit through the steam exhaust pipeline; the steam extraction flow regulating valve is installed in the steam extraction pipeline and is connected to the control module.

[0077] Specifically, a steam-molten salt heat exchanger is a device that enables heat exchange between low-temperature molten salt and high-temperature steam. The molten salt piping of the steam-molten salt heat exchanger is connected in series with the heat storage circulation piping to obtain low-temperature molten salt. The inlet of the steam piping of the steam-molten salt heat exchanger is connected to the reheat steam outlet of the boiler of the coal-fired power unit via a steam extraction piping to obtain high-temperature steam. The low-temperature molten salt and high-temperature steam can exchange heat inside the steam-molten salt heat exchanger, thereby transferring and storing the steam heat from the coal-fired power unit into the molten salt, thus achieving surplus energy storage during off-peak electricity demand periods.

[0078] The extraction steam flow regulating valve, installed in the steam extraction pipeline, is a valve device used to regulate the steam extraction rate. It is connected to a control module, which then controls the amount of steam extracted into the steam-molten salt heat exchanger. In this embodiment, the control module can control the steam extraction rate to be 10% to 20% of the total main steam volume via the extraction steam flow regulating valve to ensure the stable operation of the coal-fired power unit.

[0079] Furthermore, the steam extraction pipeline draws steam from the reheat steam outlet connected to the boiler and the intermediate-pressure cylinder. Preheating the molten salt with steam from the intermediate-temperature section effectively improves the utilization rate of low-temperature waste heat in the coal-fired power unit, achieving deep energy recovery. Simultaneously, the low-temperature steam obtained after heat exchange in the steam-molten salt heat exchanger can be connected to the condenser of the coal-fired power unit via the steam exhaust pipeline, avoiding energy waste.

[0080] Please continue to refer to Figure 3 The electric heating unit 142 can be connected to a coal-fired power unit via a power supply line to use the electrical energy generated by the coal-fired power unit to electrically heat the low-temperature molten salt in the low-temperature molten salt tank 110. Depending on the specific heating power, it can raise the molten salt from 400-450℃ to the target high temperature (510℃), or independently complete the entire heating process from 200℃ to 510℃. For example, the electric heating unit 142 connected to the coal-fired power unit via a power supply line can be a generator connected to the coal-fired power unit via a power supply line.

[0081] In one exemplary embodiment, the electric heating unit includes an electric heater connected in series in a heat storage circulation pipeline. The power supply terminal of the electric heater is connected to a coal-fired power unit, and the power regulation terminal of the electric heater is connected to a control module. Specifically, the electric heater may be an armored electric heater, with its power supply terminal connected to the generator of the coal-fired power unit to heat the low-temperature molten salt using surplus electricity during off-peak hours. Simultaneously, the power regulation terminal of the electric heater is connected to the control module to adjust the heating power of the electric heater, thereby regulating the heating of the high-temperature molten salt to the target temperature.

[0082] In one exemplary embodiment, continuing with reference to Figure 3 The extraction steam heating unit 141 and the electric heating unit 142 are sequentially installed in the thermal storage circulation pipeline A. This design allows the molten salt to flow as follows: low-temperature molten salt tank 110, extraction steam heating unit 141, electric heating unit 142, and finally into high-temperature molten salt tank 120. The extraction steam heating unit 141 undertakes the main heating process, while the electric heating unit 142 supplements the remaining heating process and regulates temperature fluctuations, forming a main-auxiliary collaborative thermal storage mode. This is highly suitable for coal-fired power units requiring deep peak-shaving capabilities, and the dominance of extraction steam heating significantly reduces thermal storage costs.

[0083] In one example, refer to Figure 1The molten salt thermal storage peak shaving system also includes: a monitoring module 160 connected to the control module 130, the monitoring module 160 being installed in the thermal storage circulation pipeline A; the monitoring module 160 is used to collect the first molten salt temperature, which is the molten salt temperature in the thermal storage circulation pipeline A behind the steam extraction heating unit 141; when the control module 130 determines that the power consumption is at its lowest point, it controls the steam extraction heating unit 141 to start operating, and when it determines that the thermal storage is incomplete based on the first molten salt temperature, it controls the electric heating unit 142 to start operating.

[0084] Specifically, the monitoring module 160 may include a temperature acquisition unit, which is installed on the heat storage circulation pipeline A on the outlet side of the steam extraction heating unit 141 to acquire the first molten salt temperature, i.e., the molten salt temperature after steam extraction heating. Simultaneously, the monitoring module 160 can transmit the acquired first molten salt temperature to the control module 130 via hardwired / industrial bus.

[0085] Furthermore, when the power consumption period is determined to be low, the control module 130 can control the extraction steam heating unit 141 to start operating, so as to indirectly exchange the steam heat energy of the coal-fired power unit with the molten salt flowing through the heat storage circulation pipeline A to achieve primary heating of the low-temperature molten salt. However, if the heat storage is determined to be incomplete based on the first molten salt temperature, that is, if the extraction steam heating alone cannot heat the molten salt to the target temperature, the electric heating unit 142 can be controlled to start operating, using electric energy to drive the electric heating to provide auxiliary heating for the molten salt, thereby raising the molten salt from 400-450℃ to the target high temperature (510℃).

[0086] The method for determining incomplete heat storage based on the first molten salt temperature is not unique; it can be based on the temperature value or the heating rate. For example, in one example, incomplete heat storage is determined if the first molten salt temperature does not reach the target temperature. In other examples, incomplete heat storage can also be determined if the heating rate of the first molten salt temperature within a preset time period does not reach the target rate. However, in the embodiments of this application, in order to directly and accurately reflect the molten salt temperature after steam extraction and heating, the failure of the first molten salt temperature to reach the target temperature can be used directly to determine whether heat storage is complete.

[0087] In one exemplary embodiment, the control module determines that an off-peak electricity consumption period has been reached upon receiving an off-peak scheduling instruction and / or a low load instruction.

[0088] Specifically, a low-peak dispatch command indicates that the current power grid operation is in a period of low electricity demand. This command can be issued through the power grid dispatch center and may include a low-peak time window, signifying that the power grid is in a period of low electricity demand within this window.

[0089] A low-load command indicates that the coal-fired power unit is currently under low load. This command can be determined by the unit's control module, specifically through data such as the unit's actual load, actual power generation, renewable energy penetration rate, or grid frequency. For example, a low-load command might be output by the control module when the unit's actual load is below 40% THA (Total Load Amount).

[0090] Furthermore, when the control module of the molten salt thermal storage peak-shaving system receives a low-valley dispatch instruction from the power grid dispatch center, or a low-load instruction from the control module of the coal-fired power unit, or both of the above instructions simultaneously, it is determined that the electricity consumption off-peak period has been reached.

[0091] In one exemplary embodiment, the control module determines that the peak electricity consumption period has been reached upon receiving a peak scheduling command and / or a high load command.

[0092] Specifically, peak dispatch instructions indicate that the current power grid operation is in a peak electricity consumption period. Peak dispatch instructions can also be issued through the power grid dispatch center, and may specifically include a peak time window, indicating that the power grid is in a peak electricity consumption period within this peak time window.

[0093] A high-load command indicates that the coal-fired power unit is currently under high load. This command can be determined by the unit's control module, specifically through data such as the unit's actual load, actual power generation, renewable energy penetration rate, or grid frequency. For example, a high-load command might be output by the control module when the unit is operating at 100% THA (Total Load Ah).

[0094] Furthermore, when the control module of the molten salt thermal storage peak-shaving system receives a peak dispatch instruction from the power grid dispatch center, or a high-load instruction from the control module of the coal-fired power unit, or both of the above instructions simultaneously, it is determined that the peak electricity consumption period has been reached.

[0095] In one exemplary embodiment, refer to Figure 1It also includes: a monitoring module 160 connected to the control module 130, the monitoring module 160 including a temperature acquisition unit, a pressure acquisition unit, and a flow acquisition unit; the temperature acquisition unit is installed in the heat storage circulation pipeline A, the heat release circulation pipeline B, the mixed heat storage module 140, and the multi-stage heat release module 150, and is used to acquire temperature data; the pressure acquisition unit is installed in the heat storage circulation pipeline A, the heat release circulation pipeline B, the mixed heat storage module 140, and the multi-stage heat release module 150, and is used to acquire pressure data; the flow acquisition unit is installed in the heat storage circulation pipeline A, the heat release circulation pipeline B, the mixed heat storage module 140, and the multi-stage heat release module 150, and is used to acquire pressure data; the flow acquisition unit is installed in the heat storage circulation pipeline B, the mixed heat storage module 140, and the multi-stage heat release module 150, and is used to acquire flow data. The system includes pipeline A, heat release circulation pipeline B, a mixed heat storage module 140, and a multi-stage heat release module 150. The control module 130 is used to determine, based on temperature data, pressure data, and flow data, that there is an abnormality in the heat storage operation, and output a shutdown command to the first molten salt pump 111 and the mixed heat storage module 140 to control the cessation of heat storage operation. Based on temperature data, pressure data, and flow data, it also determines, based on temperature data, pressure data, and flow data, that there is an abnormality in the heat release operation, and outputs a shutdown command to the second molten salt pump 121 and the multi-stage heat release module 150 to control the cessation of heat release operation.

[0096] Specifically, the temperature acquisition unit is set in the heat storage circulation pipeline A, the heat release circulation pipeline B, the mixed heat storage module 140 and the multi-stage heat release module 150. Specifically, it can be arranged at the inlet and outlet of the high temperature / low temperature molten salt storage tank, the inlet and outlet of the molten salt side and feedwater side of each stage of heat exchanger, the steam extraction pipeline, etc., to detect the temperature data at the above locations.

[0097] Pressure acquisition units are installed in the thermal storage circulation pipeline A, the heat release circulation pipeline B, the mixed thermal storage module 140, and the multi-stage heat release module 150. Specifically, they can be arranged at key nodes such as the low-temperature molten salt tank, the high-temperature molten salt tank, each stage of heat exchangers, and the steam extraction pipeline to detect pressure data at each of the above locations.

[0098] The flow acquisition unit is installed in the thermal storage circulation pipeline A, the heat release circulation pipeline B, the mixed thermal storage module 140 and the multi-stage heat release module 150. Specifically, it can be arranged in the connecting pipes of the above modules to measure the flow data of multiple media such as molten salt, steam and feedwater in the corresponding pipes.

[0099] Furthermore, the monitoring module 160 can transmit the various data collected above to the control module 130 via a signal cable, so that the control module 130 can monitor the status of the entire molten salt thermal storage peak shaving system based on temperature data, pressure data, and flow data.

[0100] In response to a detected abnormality in thermal storage operation, such as molten salt overheating during the thermal storage process, control module 130 can first output a shutdown command to the first molten salt pump 111 to cut off the molten salt flow path. It also controls the pumps and valves in the mixed thermal storage module 140 to stop operating, thereby halting the thermal storage process. Similarly, in response to a detected abnormality in heat release operation, such as an imbalance in the flow distribution of the four-stage heat release units during the heat release process, control module 130 can first output a shutdown command to the second molten salt pump 121 to cut off the molten salt heat release circulation path. It also controls the pumps and valves in the multi-stage heat release module 150 to stop operating, thereby halting the heat release process.

[0101] It is understandable that when the above-mentioned operational abnormalities occur, the control module 130 can also output alarm information to prompt technicians to check the specific conditions of the coal-fired power unit and the molten salt thermal storage peak-shaving system in order to ensure the overall stable and safe operation.

[0102] In this embodiment, the monitoring module collects molten salt temperature, pressure, flow rate, and unit power parameters in real time. When over-temperature, over-pressure, or abnormal flow occurs, the control module automatically triggers an alarm and adjusts the valves / pumps to ensure system safety.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A molten salt thermal storage peak-shaving system, characterized in that, It includes a low-temperature molten salt tank, a high-temperature molten salt tank and a control module, as well as a hybrid thermal storage module and a multi-stage heat release module connected to the control module; The outlet of the low-temperature molten salt tank is connected to the inlet of the high-temperature molten salt tank through a heat storage circulation pipeline, and the outlet of the high-temperature molten salt tank is connected to the inlet of the low-temperature molten salt tank through a heat release circulation pipeline. The mixed heat storage module is installed in the heat storage circulation pipeline, and the multi-stage heat release module is installed in the heat release circulation pipeline. The mixed heat storage module and the multi-stage heat release module are also connected to a coal-fired power unit. When the control module determines that the electricity consumption period has reached a low point, it controls the hybrid thermal storage module to start operation and use the energy of the coal-fired power unit to heat the low-temperature molten salt in the low-temperature molten salt tank into high-temperature molten salt in the thermal storage circulation pipeline through at least one heating method, and then store it in the high-temperature molten salt tank. When the control module determines that the peak electricity consumption period has been reached, it controls the multi-stage heat release module to start operation. In the heat release circulation pipeline, the heat of the high-temperature molten salt in the high-temperature molten salt tank is released to the coal-fired power unit in stages, and the resulting low-temperature molten salt is stored in the low-temperature molten salt tank.

2. The molten salt thermal storage peak-shaving system according to claim 1, characterized in that, The multi-stage heat release module includes a series of multi-stage molten salt-feedwater heat exchangers. The molten salt side of each stage of the molten salt-feedwater heat exchanger is connected in series through the heat release circulation pipeline. The feedwater side of each stage of the molten salt-feedwater heat exchanger is connected through pipelines to one or more of the multi-stage high-pressure heating components, deaerator, and multi-stage low-pressure heating components of the coal-fired power unit.

3. The molten salt thermal storage peak-shaving system according to claim 2, characterized in that, The multi-stage heat release module includes a first-stage molten salt-feedwater heat exchanger, a second-stage molten salt-feedwater heat exchanger, a third-stage molten salt-feedwater heat exchanger, and a fourth-stage molten salt-feedwater heat exchanger. The heat release circulation pipeline is connected in series with the first-stage molten salt-feed water heat exchanger, the second-stage molten salt-feed water heat exchanger, the third-stage molten salt-feed water heat exchanger, and the molten salt side of the fourth-stage molten salt-feed water heat exchanger. The feedwater sides of the first-stage molten salt-feedwater heat exchanger and the second-stage molten salt-feedwater heat exchanger are connected to the condensate pipeline of the multi-stage high-pressure heating assembly via pipelines. The feedwater side of the third-stage molten salt-feedwater heat exchanger is connected to the condensate pipeline of the deaerator via pipelines. The feedwater side of the fourth-stage molten salt-feedwater heat exchanger is connected to the condensate pipeline of the multi-stage low-pressure heating assembly via pipelines.

4. The molten salt thermal storage peak-shaving system according to claim 1, characterized in that, The hybrid thermal storage module includes a steam extraction heating unit and an electric heating unit, both of which are installed in the thermal storage circulation pipeline. The steam extraction heating unit is connected to the coal-fired power unit through a steam extraction pipeline, so as to use the heat of the steam generated by the coal-fired power unit to steam heat the low-temperature molten salt in the low-temperature molten salt tank. The electric heating unit is connected to the coal-fired power unit via a power supply line to use the electrical energy generated by the coal-fired power unit to electrically heat the low-temperature molten salt in the low-temperature molten salt tank.

5. The molten salt thermal storage peak-shaving system according to claim 4, characterized in that, The steam extraction heating unit and the electric heating unit are sequentially arranged in the heat storage circulation pipeline; The molten salt thermal storage peak shaving system further includes: a monitoring module connected to the control module, wherein the monitoring module is installed in the thermal storage circulation pipeline; The monitoring module is used to collect the first molten salt temperature, which is the molten salt temperature in the heat storage circulation pipeline behind the steam extraction heating unit. When the control module determines that the electricity consumption period is low, it controls the steam extraction heating unit to start operating. When it determines that the heat storage is incomplete based on the first molten salt temperature, it controls the electric heating unit to start operating.

6. The molten salt thermal storage peak-shaving system according to claim 4, characterized in that, The extraction steam heating unit includes a steam-molten salt heat exchanger and an extraction steam flow regulating valve; The molten salt pipeline of the steam-molten salt heat exchanger is connected in series with the heat storage circulation pipeline. The inlet of the steam pipeline of the steam-molten salt heat exchanger is connected to the reheat steam outlet of the boiler of the coal-fired power unit through the steam extraction pipeline. The outlet of the steam pipeline is connected to the condenser of the coal-fired power unit through the steam exhaust pipeline. The steam extraction flow regulating valve is installed in the steam extraction pipeline and is connected to the control module.

7. The molten salt thermal storage peak-shaving system according to claim 4, characterized in that, The electric heating unit includes an electric heater connected in series with the heat storage circulation pipeline. The power supply terminal of the electric heater is connected to the coal-fired power unit, and the power adjustment terminal of the electric heater is connected to the control module.

8. The molten salt thermal storage peak-shaving system according to any one of claims 1 to 7, characterized in that, Upon receiving a low-peak scheduling command and / or a low-load command, the control module determines that the electricity consumption off-peak period has been reached. Upon receiving peak scheduling instructions and / or high load instructions, the control module determines that the peak electricity consumption period has been reached.

9. The molten salt thermal storage peak-shaving system according to any one of claims 1 to 7, characterized in that, It also includes a first molten salt pump and a second molten salt pump. The first molten salt pump is located on the heat storage circulation pipeline near the outlet of the low-temperature molten salt tank, and the second molten salt pump is located on the heat release circulation pipeline near the outlet of the high-temperature molten salt tank.

10. The molten salt thermal storage peak-shaving system according to claim 9, characterized in that, Also includes: The monitoring module connected to the control module includes a temperature acquisition unit, a pressure acquisition unit, and a flow acquisition unit. The temperature acquisition unit is installed in the heat storage circulation pipeline, the heat release circulation pipeline, the hybrid heat storage module, and the multi-stage heat release module to acquire temperature data; the pressure acquisition unit is installed in the heat storage circulation pipeline, the heat release circulation pipeline, the hybrid heat storage module, and the multi-stage heat release module to acquire pressure data; the flow acquisition unit is installed in the heat storage circulation pipeline, the heat release circulation pipeline, the hybrid heat storage module, and the multi-stage heat release module to acquire flow data. The control module is used to determine, based on the temperature data, pressure data, and flow data, that there is an abnormality in the thermal storage operation, and output a shutdown command to the first molten salt pump and the mixed thermal storage module to control the cessation of thermal storage operation; and to determine, based on the temperature data, pressure data, and flow data, that there is an abnormality in the heat release operation, and output a shutdown command to the second molten salt pump and the multi-stage heat release module to control the cessation of heat release operation.

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