A multi-energy synergistic utilization system based on molten salt thermal storage system

Abstract

This utility model relates to the field of molten salt thermal storage technology, specifically to a multi-energy synergistic utilization system based on a molten salt thermal storage system. It includes a molten salt circulation system and a molten salt heat tracing system. The molten salt circulation system includes a cold salt tank, a heater, a hot salt tank, and several key pieces of equipment connected via molten salt pipelines. The molten salt heat tracing system includes an induction coil, a variable frequency power supply connected to the induction coil, and a controller connected to the variable frequency power supply. The induction coil can be wound around the key equipment and the molten salt pipelines in important areas. The induction coil can heat the key equipment in important areas and the molten salt pipelines connecting them. The alternating current generated by the variable frequency power supply produces an alternating magnetic field, inducing a turbine current in the key equipment and molten salt pipelines. This turbine current flows angularly along the pipeline. Since the key equipment and the molten salt pipelines themselves have a certain resistance, non-contact heating can be achieved.

Description

Technical Field

[0001] This utility model relates to the field of molten salt thermal energy storage technology, specifically to a multi-energy synergistic utilization system based on molten salt thermal energy storage. Background Technology

[0002] Molten salt is an excellent heat transfer and energy storage medium. Due to its advantages of "four highs and three lows" (high operating temperature, high thermal stability, high specific heat capacity, high convective heat transfer coefficient, low viscosity, low saturated vapor pressure, and low price), it has become one of the most recognized heat transfer and energy storage media in the field of solar thermal power generation.

[0003] The characteristic of molten salt solidifying at room temperature significantly restricts the further development of molten salt thermal storage technology. To avoid solidification, current molten salt systems often employ heating with heat tracing cables, covering the entire molten salt system. However, this method requires heating the insulation of the entire pipeline to above the minimum operating temperature of the molten salt, thus consuming a large amount of electricity, resulting in degraded energy use and significant waste. Furthermore, this method heats the molten salt pipeline through heat conduction. Due to the small contact area between the heat tracing cable and the molten salt pipeline, and the impossibility of a tight fit, with insulation or air gaps in between, the heating speed is relatively slow, making it difficult to meet the rapid response requirements of energy storage systems. Utility Model Content

[0004] In view of this, the present invention provides a multi-energy synergistic utilization system based on a molten salt thermal storage system to solve the problems of high energy consumption and slow heating speed in existing methods.

[0005] This utility model provides a multi-energy collaborative utilization system based on a molten salt thermal storage system, including a molten salt circulation system and a molten salt heat tracing system. The molten salt circulation system includes a cold salt tank, a heater, a hot salt tank, and several key devices connected through molten salt pipelines. The molten salt heat tracing system includes an induction coil, a variable frequency power supply connected to the induction coil, and a controller connected to the variable frequency power supply.

[0006] The molten salt circulation system is divided into several key areas, each containing critical equipment and molten salt pipes for connecting the equipment. Induction coils are positioned corresponding to these key areas and are adapted to heat them. The induction coils can be wound around the critical equipment and molten salt pipes within the key areas.

[0007] Induction coils can be used to heat critical equipment and molten salt pipes connecting them within important areas. Replacing the heating tape in conventional molten salt systems, induction coils generate an alternating magnetic field through an alternating current produced by a frequency converter. This induces a turbine current in the critical equipment and molten salt pipes (mostly made of steel). The turbine current flows angularly along the pipes, and the inherent resistance of the equipment and pipes enables non-contact heating. The induction coils can be centrally managed and controlled by a controller. This application heats critical equipment and molten salt pipes using turbine currents, requiring less electrical energy and eliminating the need for heating insulation. It also offers rapid heating and response.

[0008] In one optional embodiment, the molten salt heat tracing system further includes a molten salt-air heat exchanger, an air circulation pump, and an air inlet valve connected in sequence via pipelines. The molten salt-air heat exchanger is located in the critical area and is adapted to heat the air using the temperature of the molten salt. The air inlet valve is connected to the molten salt circulation system via pipelines and is also connected to the controller.

[0009] When preheating the molten salt pipeline, the controller controls the air circulation pump and the frequency converter to turn on and controls the air inlet valve to open. Under the action of the air circulation pump, the hot air obtained by the molten salt-air heat exchanger flows inside the molten salt circulation system, carrying away the heat generated on the molten salt pipeline wound with the induction coil, so that the temperature of the entire molten salt pipeline tends to be uniform until the molten salt pipeline and equipment in the molten salt circulation system meet the temperature required for the start-up and operation of the molten salt system.

[0010] In one alternative embodiment, the molten salt heat tracing system further includes a plurality of thermocouples disposed on the molten salt pipe and connected to the controller, the thermocouples being adapted to obtain the temperature of the molten salt pipe.

[0011] The thermocouple can transmit the obtained temperature signal to the controller. The controller can preset the temperature rise curve according to the application scenario of the molten salt circulation system. The controller can send instructions to the frequency converter power supply according to the temperature signal of the thermocouple to control the current flowing through the induction coil and ensure that the actual temperature change meets the preset.

[0012] In one optional embodiment, the molten salt circulation system further includes a molten salt-steam heat exchanger connected to the hot salt tank via a molten salt pipeline. The molten salt-steam heat exchanger is adapted to obtain steam through the hot salt tank. The inlet valve is connected to the molten salt-steam heat exchanger via a pipeline, and a molten salt valve is connected between the inlet valve and the molten salt-steam heat exchanger. The molten salt valve is connected to the controller.

[0013] In one optional embodiment, the molten salt heat tracing system further includes an exhaust valve, an air-hot water heat exchanger, and a hot water tank connected in sequence by pipelines. The exhaust valve is connected to the molten salt-steam heat exchanger by pipelines, and the exhaust valve is connected to a controller.

[0014] It is important to note that during the preheating of the molten salt pipeline, the molten salt valve is closed and the air outlet valve is open. After preheating is complete, the molten salt-air heat exchanger, air circulation pump, and air inlet valve can continue to operate. The hot air in the molten salt pipeline passes through the entire molten salt circulation system and then enters the air-hot water heat exchanger through the air outlet valve. The generated hot water is stored in a hot water tank and can be directly used to provide heating or domestic hot water to surrounding residents.

[0015] In one alternative embodiment, the molten salt heat tracing system further includes a steam valve and a power generation system connected by a pipeline, the steam valve being connected to the molten salt-steam heat exchanger by a pipeline, and the steam valve being connected to a controller.

[0016] After preheating, the molten salt circulation system can enter normal operation. The molten salt-steam heat exchanger can generate high-temperature steam, which is then used to generate electricity to supply power to the grid.

[0017] In one optional embodiment, the molten salt tracing system further includes a movable induction coil and a movable frequency converter connected to the movable induction coil. When solidification occurs in a localized section of the molten salt pipeline, the movable induction coil and the movable frequency converter can be used for targeted melting.

[0018] In one optional implementation, the power generation system is connected to the movable induction coil. The power generation system can charge and discharge the movable induction coil, thus avoiding peak shaving and valley filling of the power grid.

[0019] In one alternative embodiment, the molten salt pipeline is divided into sections with local molten salt collection zones, and each local molten salt collection zone is equipped with an induction coil.

[0020] In one alternative embodiment, the inner wall surface of the molten salt pipe is treated with a relative permeability enhancement process.

[0021] Increasing the relative magnetic permeability of the inner wall of the molten salt pipe allows the turbine current to generate more heat inside the molten salt pipe, thus improving heating efficiency. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a connection diagram of an embodiment of the present utility model.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Cold salt tank; 2. Heater; 3. Hot salt tank; 4. Molten salt pipeline; 5. Molten salt-air heat exchanger; 6. Air circulation pump; 7. Inlet valve; 9. Molten salt-steam heat exchanger; 10. Molten salt valve; 11. Outlet valve; 12. Air-hot water heat exchanger; 13. Hot water tank; 14. Steam valve; 15. Power generation system. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] The following is combined Figure 1 The following describes embodiments of the present invention.

[0028] According to an embodiment of this utility model, a multi-energy synergistic utilization system based on a molten salt thermal storage system is provided, including a molten salt circulation system and a molten salt heat tracing system. The molten salt circulation system includes a cold salt tank 1, a heater 2, a hot salt tank 3, and several key devices connected by a molten salt pipeline 4. The molten salt heat tracing system includes an induction coil, a variable frequency power supply connected to the induction coil, and a controller connected to the variable frequency power supply. In the molten salt circulation system, the low-temperature molten salt in the cold salt tank 1 can enter the heater 2 through a molten salt pump, and the heated high-temperature molten salt enters the hot salt tank 3 for storage, completing the molten salt thermal storage cycle. Figure 1 The text describes the direction of hot air (heat) flow.

[0029] The heater 2 can vary depending on the actual scenario and conditions. It can be a solar thermal absorption heater, an electric heater, or a heater for various fuel combustion. It can be applied to various systems or scenarios such as solar thermal power generation system 15, molten salt thermal storage peak shaving and frequency regulation system, and molten salt comprehensive utilization system.

[0030] The molten salt circulation system is divided into several key areas, each containing critical equipment and molten salt pipes 4 for connecting the critical equipment. Induction coils are positioned corresponding to these key areas and are suitable for heating them. The induction coils can be wound around the critical equipment and molten salt pipes 4 within the key areas. Specifically, they can be wound around the molten salt pump, molten salt valve 10, and molten salt pipes 4 within the key areas. This application reduces costs by not winding the induction coils along the entire length of the molten salt pipes 4, but rather placing them in key areas. This optimizes the coverage length of the induction coils on the molten salt pipes 4 while ensuring normal heat tracing and operation of the system. The induction coils can be made as close as possible to the molten salt pipes 4, and the number of turns, frequency, and current of the induction coils, as well as the frequency and current of the variable frequency power supply, can be reasonably set according to the actual heat tracing requirements to reduce heat tracing energy consumption. A suitable variable frequency power supply frequency range can be selected based on the actual material and application scenario requirements; the selectable variable frequency is 50-1000Hz. The critical equipment generally includes the molten salt pump and the molten salt valve 10, and the area where the molten salt pump or molten salt valve 10 is located is generally designated as a key area. The controller can be an intelligent control system.

[0031] Induction coils can be used to heat critical equipment within important areas and the molten salt pipes 4 connecting these equipment. Replacing the heating tape in conventional molten salt systems, induction coils generate an alternating magnetic field through an alternating current produced by a frequency converter. This induces a turbine current in the critical equipment and molten salt pipes 4 (mostly made of steel). The turbine current flows angularly along the pipes. Since the critical equipment and molten salt pipes 4 have a certain resistance, non-contact heating is achieved. The induction coils can be centrally managed and controlled by a controller. This application heats the critical equipment and molten salt pipes 4 using turbine current, requiring less electrical energy and eliminating the need to heat insulation cotton. It also offers rapid heating and response.

[0032] It should be noted that if the outer layer of the molten salt pipe 4 is provided with insulation cotton, a metal outer layer can be provided on the outside of the insulation cotton, and the induction coil can be directly wound on the metal outer layer, or the molten salt pipe 4 can be heated by turbine current.

[0033] In one optional embodiment, the molten salt heat tracing system further includes a molten salt-air heat exchanger 5, an air circulation pump 6, and an air inlet valve 7 connected in sequence via pipelines. The molten salt-air heat exchanger 5 is located in the critical area and is adapted to heat the air using the temperature of the molten salt. The air inlet valve 7 is connected to the molten salt circulation system via pipelines and is also connected to the controller.

[0034] When preheating the molten salt pipeline 4, the controller controls the air circulation pump 6 and the frequency converter to turn on and controls the air inlet valve 7 to open. Under the action of the air circulation pump 6, the hot air obtained by the molten salt-air heat exchanger 5 flows inside the molten salt circulation system, carrying away the heat generated on the molten salt pipeline 4 around which the induction coil is wound, so that the temperature of the entire molten salt pipeline 4 tends to be uniform until the molten salt pipeline 4 and the equipment in the molten salt circulation system meet the temperature required for the start-up and operation of the molten salt system.

[0035] In one alternative embodiment, the molten salt heat tracing system further includes a plurality of thermocouples disposed on the molten salt pipe 4 and connected to the controller, the thermocouples being adapted to obtain the temperature of the molten salt pipe 4.

[0036] The thermocouple can transmit the obtained temperature signal to the controller. The controller can preset the temperature rise curve according to the application scenario of the molten salt circulation system. The controller can send instructions to the frequency converter power supply according to the temperature signal of the thermocouple to control the current flowing through the induction coil and ensure that the actual temperature change meets the preset.

[0037] In an optional embodiment, the molten salt circulation system further includes a molten salt-steam heat exchanger 9 connected to the hot salt tank 3 via a molten salt pipeline 4. The molten salt-steam heat exchanger 9 is adapted to obtain steam through the hot salt tank 3. An air inlet valve 7 is connected to the molten salt-steam heat exchanger 9 via a pipeline, and a molten salt valve 10 is connected between the air inlet valve 7 and the molten salt-steam heat exchanger 9. The molten salt valve 10 is connected to the controller.

[0038] In one optional embodiment, the molten salt heat tracing system further includes an exhaust valve 11, an air-hot water heat exchanger 12, and a hot water tank 13 connected in sequence by pipelines. The exhaust valve 11 is connected to the molten salt-steam heat exchanger 9 by pipelines, and the exhaust valve 11 is connected to a controller.

[0039] It should be noted that when preheating the molten salt pipeline 4, the molten salt valve 10 is closed and the air outlet valve 11 is open. After preheating is complete, the molten salt-air heat exchanger 5, the air circulation pump 6, and the air inlet valve 7 can continue to operate. The hot air in the molten salt pipeline 4 passes through the entire molten salt circulation system and enters the air-hot water heat exchanger 12 through the air outlet valve 11. The generated hot water is stored in the hot water tank 13, which can directly provide heating or domestic hot water to the surrounding residents.

[0040] In an optional embodiment, the molten salt heat tracing system further includes a steam valve 14 and a power generation system 15 connected by a pipeline. The steam valve 14 is connected to the molten salt-steam heat exchanger 9 by a pipeline and is also connected to a controller.

[0041] After preheating, the molten salt circulation system can enter normal operation. The molten salt-steam heat exchanger 9 generates high-temperature steam, which is then used to generate electricity via the power generation system 15 to supply power to the grid. It should be noted that the steam valve 14 is closed during the preheating of the molten salt pipeline 4. The power generation system 15 can be a steam turbine-power generation system.

[0042] In one optional embodiment, the molten salt heating system further includes a movable induction coil and a movable frequency converter connected to the movable induction coil. When localized solidification occurs in the molten salt pipe 4, the movable induction coil and the movable frequency converter can be used for targeted melting. To improve heating efficiency, when heating with the movable induction coil, the outer metal layer on the insulation layer can be lifted, allowing for non-contact heating of the molten salt pipe 4 through the insulation cotton. Besides the winding method, the movable induction coil can also be configured as a semi-cylindrical shape that fits snugly against the molten salt pipe 4, improving the convenience of heating.

[0043] In one optional embodiment, the power generation system 15 is connected to the movable induction coil. The power generation system 15 can charge and discharge the movable induction coil, and by simultaneously charging and discharging the movable induction coil through the power generation system 15, peak shaving and valley filling of the power grid can be avoided.

[0044] In one optional embodiment, the molten salt pipe 4 is segmented into localized molten salt collection sections, each equipped with an induction coil. In these localized collection sections, gravity can be used to concentrate the residual molten salt within the pipe 4; for example, the pipe 4 can be configured with a concave bend in these sections. The induction coil can be wound around these localized collection sections. It should be noted that the bends inherent in the molten salt pipe 4 itself also serve to concentrate residual molten salt; therefore, induction coils can be placed at the bends inherent in the molten salt pipe 4.

[0045] In one alternative embodiment, the inner wall surface of the molten salt pipe 4 undergoes a relative magnetic permeability enhancement treatment. Specifically, a material with high magnetic permeability can be coated onto the inner wall surface of the molten salt pipe 4, such as a layer of magnetic material like nickel or cobalt plated on the surface.

[0046] Increasing the relative magnetic permeability of the inner wall of the molten salt pipe 4 allows the turbine current to generate more heat inside the molten salt pipe 4, thereby improving heating efficiency.

[0047] First, this application utilizes alternating current to generate an alternating magnetic field, thereby producing a turbine current in the molten salt pipe 4, achieving heating of the molten salt pipe 4. This avoids the heat transfer method of conventional heating cables, which requires heat to be conducted from the outside in, reducing heat loss, shortening the heat transfer path, improving electric heating efficiency, and providing a relatively fast heating rate, thus saving valuable time for rapid equipment startup. Second, this application includes a localized molten salt collection section, avoiding the need for a full-pipeline heating system, further reducing equipment costs and energy consumption. Third, this application includes a molten salt-air heat exchanger 5, an air circulation pump 6, and an air inlet valve 7, allowing the use of molten salt-generated hot air as an auxiliary heating medium, reducing the degraded use of high-quality energy (electricity). Furthermore, to ensure no dead zones where the molten salt solidifies, this application also includes a movable coil.

[0048] In summary, this application utilizes the physical properties of the system to provide a novel approach to molten salt heat tracing systems, reducing heat tracing losses, improving system efficiency, filling the gap in novel heat tracing methods, enhancing economic efficiency, and providing strong support for the healthy development of molten salt thermal storage.

[0049] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A multi-energy collaborative utilization system based on a fused salt heat storage system, characterized in that, It includes a molten salt circulation system and a molten salt heat tracing system. The molten salt circulation system includes a cold salt tank (1), a heater (2), a hot salt tank (3) connected by a molten salt pipeline (4), and several key devices. The molten salt heat tracing system includes an induction coil, a frequency converter connected to the induction coil, and a controller connected to the frequency converter. The molten salt circulation system is provided with several important areas, and key equipment and molten salt pipes (4) for connecting the key equipment are provided in the important areas. The induction coil is provided in correspondence with the important areas and is suitable for heating the important areas.

2. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 1, characterized in that, The molten salt heat tracing system also includes a molten salt-air heat exchanger (5), an air circulation pump (6), and an air inlet valve (7) connected in sequence by pipelines. The molten salt-air heat exchanger (5) is located in the important area and is suitable for heating air using the temperature of molten salt. The air inlet valve (7) is connected to the molten salt circulation system by pipelines and is also connected to the controller.

3. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 1, characterized in that, The molten salt heat tracing system also includes several thermocouples, which are installed on the molten salt pipe (4) and connected to the controller. The thermocouples are adapted to obtain the temperature of the molten salt pipe (4).

4. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 2, characterized in that, The molten salt circulation system also includes a molten salt-steam heat exchanger (9) connected to the hot salt tank (3) via a molten salt pipeline (4). The molten salt-steam heat exchanger (9) is adapted to obtain steam from the hot salt tank (3). The inlet valve (7) is connected to the molten salt-steam heat exchanger (9) via a pipeline, and a molten salt valve (10) is connected between the inlet valve (7) and the molten salt-steam heat exchanger (9). The molten salt valve (10) is connected to the controller.

5. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 4, characterized in that, The molten salt heat tracing system also includes an exhaust valve (11), an air-hot water heat exchanger (12), and a hot water tank (13) connected in sequence by pipelines. The exhaust valve (11) is connected to the molten salt-steam heat exchanger (9) by pipelines, and the exhaust valve (11) is connected to the controller.

6. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 4, characterized in that, The molten salt heat tracing system also includes a steam valve (14) and a power generation system (15) connected by a pipeline. The steam valve (14) is connected to the molten salt-steam heat exchanger (9) by a pipeline, and the steam valve (14) is connected to the controller.

7. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 6, characterized in that, The molten salt heat tracing system also includes a movable induction coil and a movable frequency converter connected to the movable induction coil.

8. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 7, characterized in that, The power generation system (15) is connected to the mobile induction coil.

9. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 1, characterized in that, The molten salt pipeline (4) is divided into sections with local molten salt collection zones, and each local molten salt collection zone is equipped with an induction coil.

10. The multi-energy synergistic utilization system based on molten salt thermal storage system according to claim 1, characterized in that, The inner wall surface of the molten salt pipe (4) is subjected to a relative magnetic permeability enhancement treatment.

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