Modular molten salt-based heat storage system based on volumetric absorption

Abstract

This invention discloses a modular molten salt thermal storage system based on volumetric absorption, belonging to the field of solar thermal power generation technology. It includes a heat collection component, a heat storage tank, a porous media baffle, a drive mechanism, at least two molten salt storage tanks, a first heat exchanger, a second heat exchanger, and connecting pipelines. The heat collection component is located at the top of the heat storage tank; the porous media baffle is located inside the heat storage tank and is driven by the drive mechanism to move vertically; the heat storage tank has a heating rod, a molten salt outlet, and a molten salt inlet; the molten salt storage tank is connected to the molten salt inlet through the first heat exchanger, and the molten salt outlet is connected to the molten salt storage tank through the second heat exchanger, forming a molten salt circulation loop. This invention achieves volumetric absorption through the porous media baffle, effectively improving the photothermal conversion efficiency and the uniformity of molten salt melting; the drive mechanism enables precise baffle displacement, ensuring a stable and controllable melting process; and the modular parallel design allows for flexible system power adjustment and fault isolation, improving system reliability and efficiency.

Description

Technical Field

[0001] This invention relates to the field of solar thermal power generation technology, and in particular to a modular molten salt thermal storage system based on volumetric absorption. Background Technology

[0002] In solar thermal power generation technology, molten salt is widely used as a heat transfer and storage medium due to its excellent heat storage performance and stability. The operation of a molten salt thermal storage system typically involves the melting of solid molten salt and the heat storage and exchange of liquid molten salt. However, existing molten salt thermal storage systems suffer from the following technical drawbacks:

[0003] First, current molten salt thermal storage systems mostly employ surface absorption, where heat must be transferred to the molten salt through a medium such as the pipe wall. This method suffers from low heat transfer efficiency, uneven temperature distribution within the molten salt, and poor salt melting efficiency. Especially when using solar energy for direct salt melting, the heat transfer method is further slowed down by the limited solar radiation intensity, resulting in low efficiency.

[0004] Secondly, the inherent high reflectivity of solid molten salt surfaces causes a large amount of incident light energy to be reflected and not effectively absorbed, significantly reducing the efficiency of light energy utilization. This characteristic has become a key bottleneck restricting the overall performance improvement of concentrated solar power (CSP) systems and seriously affecting the system's operating efficiency.

[0005] Therefore, there is an urgent need to develop a molten salt thermal storage system that can overcome the above-mentioned defects, improve the efficiency of direct solar salt conversion, reduce light energy reflection loss, and realize modular storage and operation of molten salt. Summary of the Invention

[0006] The purpose of this invention is to provide a modular molten salt thermal storage system based on volumetric absorption, aiming to solve the problems of low molten salt melting efficiency, low light energy utilization efficiency, and insufficient system operational flexibility in existing technologies. This system significantly improves molten salt melting efficiency and photothermal conversion efficiency through the principle of volumetric absorption and modular design, while also enhancing the system's operational flexibility and reliability.

[0007] To achieve the above objectives, the present invention provides a modular molten salt thermal storage system based on volumetric absorption, comprising a heat collection component, a thermal storage tank, a porous medium baffle, a drive mechanism, at least two molten salt storage tanks, a first heat exchanger, a second heat exchanger, and connecting pipelines; the heat collection component is disposed on the upper part of the thermal storage tank; the porous medium baffle is disposed inside the thermal storage tank and configured to move vertically under the drive of the drive mechanism; a heating rod is provided at the lower part of the thermal storage tank, a molten salt outlet is provided at the upper end of the thermal storage tank, and a molten salt inlet is provided at the lower end; the outlet end of the molten salt storage tank is connected to the molten salt inlet of the thermal storage tank through the first heat exchanger, and the molten salt outlet of the thermal storage tank is connected to the inlet end of the molten salt storage tank through the second heat exchanger, forming a molten salt circulation loop.

[0008] Preferably, the porous dielectric separator includes a separator body and an absorption-heat conduction structure filled therein, the absorption-heat conduction structure including an upper absorption part and a lower heat conduction part; the upper absorption part is made of black foamed silicon carbide porous dielectric, and the lower heat conduction part is made of foamed copper porous dielectric.

[0009] Preferably, the drive mechanism includes a pull ring, a rope, a vertical pulley, a horizontal pulley, a fixed pulley, a drive shaft, a motor, and a controller; the pull ring is fixedly connected to the porous medium partition; the vertical and horizontal pulleys are disposed at the top of the inner wall of the heat storage tank; one end of the rope is connected to the pull ring, and the other end passes through the vertical and horizontal pulleys in sequence, and then winds around the drive shaft through the fixed pulley; the drive shaft is connected to the output shaft of the motor, and the motor is electrically connected to the controller.

[0010] Preferably, the driving mechanism further includes a guide rail, which is vertically disposed on the inner wall of the heat storage tank, and the edge of the porous medium partition is provided with a sliding groove that matches the guide rail, and the porous medium partition slides along the guide rail.

[0011] Preferably, the driving mechanism further includes a counterweight block, which is disposed above the porous medium partition.

[0012] Preferably, the porous medium partition is covered with a heat-insulating material.

[0013] Preferably, the number of molten salt storage tanks is three; the outlet ends of the three molten salt storage tanks are connected in parallel and then connected to the inlet end of the first heat exchanger, and the inlet ends of the three molten salt storage tanks are connected in parallel and then connected to the outlet end of the second heat exchanger.

[0014] Preferably, the connecting pipeline includes a first salt outlet pipeline and a first salt inlet pipeline; the first salt outlet pipeline includes a main salt outlet pipe and a plurality of salt outlet branch pipes connected in parallel to the main salt outlet pipe, the main salt outlet pipe is connected to the inlet end of the first heat exchanger, each salt outlet branch pipe is connected to the outlet end of one of the molten salt storage tanks, the main salt outlet pipe is equipped with a flow regulating valve, and each salt outlet branch pipe is equipped with a shut-off valve; the first salt inlet pipeline includes a main salt inlet pipe and a plurality of salt inlet branch pipes connected in parallel to the main salt inlet pipe, the main salt inlet pipe is connected to the outlet end of the second heat exchanger, each salt inlet branch pipe is connected to the inlet end of one of the molten salt storage tanks, and each salt inlet branch pipe is equipped with a shut-off valve.

[0015] Preferably, the heat storage tank, the first heat exchanger, the second heat exchanger, and each connecting pipe are all provided with an external heat insulation structure.

[0016] Preferably, the heating rod is an electric heating rod.

[0017] Therefore, the modular molten salt thermal storage system based on volumetric absorption using the above structure of the present invention has the following beneficial effects:

[0018] (1) This invention uses a porous dielectric partition to achieve volumetric absorption. The upper layer of black foamed silicon carbide porous dielectric has good light absorption performance and can efficiently absorb solar radiation energy transferred by the heat collection component; the lower layer of foamed copper porous dielectric has excellent thermal conductivity and a large specific surface area, which can quickly and uniformly transfer heat to the solid molten salt in contact. This design effectively solves the problem of high surface reflectivity and low absorptivity of solid molten salt, and avoids the uneven internal temperature of molten salt caused by traditional surface heating through volumetric heating, significantly improving the melting rate and overall thermal efficiency of molten salt.

[0019] (2) Through the design of the driving mechanism (including a motor, transmission shaft, pulley block, guide rail and counterweight), this invention enables the precise and stable vertical movement of the porous medium baffle in the heat storage tank. The baffle can be adjusted in position according to the melting process, always maintaining good contact with the surface of the solid molten salt, ensuring that the molten salt is heated uniformly from top to bottom, avoiding local overheating or overcooling, achieving efficient and uniform melting of the molten salt, and preventing energy loss caused by insufficient melting.

[0020] (3) This invention adopts a modular operation mode, with multiple molten salt storage tanks connected in parallel in the heat exchange circuit. By controlling the shut-off valves on each branch pipe, some molten salt storage tanks can be flexibly opened or closed according to actual load requirements, thereby adjusting the overall operating power of the system. When some modules need maintenance or malfunction, they can be isolated separately without affecting the normal operation of other modules, effectively improving the overall reliability and operating efficiency of the system.

[0021] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a modular molten salt thermal storage system based on volumetric absorption according to the present invention.

[0023] Figure 2 This is a top view of the heat collection component and the heat storage tank in this invention;

[0024] Figure 3 This is a schematic diagram of the internal structure of the porous media separator in this invention;

[0025] Figure 4 This is a top view of the porous dielectric partition in this invention;

[0026] Figure Labels

[0027] 1-Heat collector; 2-Storage tank cover; 3-Storage tank; 301-Heating rod; 4-Porous medium baffle; 401-Counterweight; 402-Pull ring; 403-Vertical pulley; 404-Guide rail; 405-Black foam SiC porous medium; 406-Foam copper porous medium; 5-Molten salt outlet; 6-Molten salt inlet; 7-First heat exchanger; 8-Second heat exchanger; 9-Molten salt storage tank; 10-Flow regulating valve; 11-Stop valve; 12-First salt outlet pipeline; 1201-Salt outlet main pipe; 1202-Salt outlet branch pipe; 13-First salt inlet pipeline; 1301-Salt inlet main pipe; 1302-Salt inlet branch pipe; 1401-Horizontal pulley; 1402-Fixed pulley; 1403-Drive shaft; 1404-Motor; 1405-Controller. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0029] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0030] Example

[0031] like Figure 1-3 As shown, this invention provides a modular molten salt thermal storage system based on volumetric absorption, including a heat collection component 1, a thermal storage tank 3, three molten salt storage tanks 9, a first heat exchanger 7, a second heat exchanger 8, a guide rail 404, a porous medium baffle 4, and a heating rod 301. The heat collection component 1 has an open-top structure and is located in the upper part of the thermal storage tank 3, used to collect and introduce solar radiation energy. The thermal storage tank cover 2 is located at the upper end of the thermal storage tank 3, used to close the upper opening of the thermal storage tank 3, and together with the heat collection component 1, it forms the top structure of the thermal storage tank 3. A porous medium baffle 4 is provided in the middle of the thermal storage tank 3, and is moved by a pull ring 402 and a counterweight 401 through the guide rail 404 provided in the thermal storage tank 3.

[0032] like Figure 3 and Figure 4 As shown, the porous dielectric partition 4 is externally insulated, effectively reducing heat loss. The porous dielectric partition 4 employs a double-layer structure: the upper part is filled with black foamed SiC porous dielectric 405, and the lower part is filled with foamed copper porous dielectric 406. The black foamed SiC porous dielectric 405 has excellent light absorption properties, enabling it to efficiently absorb solar radiation energy transferred from the heat collection component 1 and convert it into heat energy. Simultaneously, the foamed copper porous dielectric 406 possesses excellent thermal conductivity and a large specific surface area, facilitating rapid heat conduction and uniform distribution within the molten salt.

[0033] When the porous dielectric partition 4 is placed on the surface of the solid molten salt, the black foamed SiC porous dielectric 405 can fully absorb the heat transferred from the heat collection component. The foamed copper porous dielectric 406 rapidly transfers heat to the solid molten salt in contact with it. As heat accumulates, the molten salt gradually melts, forming a liquid molten salt region. The presence of the porous dielectric partition ensures that the molten salt is heated uniformly, avoiding local overheating or undercooling, thus achieving efficient and uniform melting of the molten salt.

[0034] The vertical displacement of the porous medium partition 4 is precisely controlled by a drive mechanism, such as... Figure 2 As shown. A pull ring 402 is fixedly installed on the porous medium partition 4. A vertical pulley 403 and a horizontal pulley 1401 are provided above the inner wall of the heat storage tank 3. The pull ring 402 passes through the vertical pulley 403 and the horizontal pulley 1401 in sequence by a rope. The horizontal pulley 1401 is connected to the drive shaft 1403 through a fixed pulley 1402. The drive shaft 1403 is driven by a motor 1404, which is controlled by a controller 1405. At the same time, a counterweight 401 is provided above the porous medium partition 4 to assist in balancing and adjusting the moving resistance of the partition.

[0035] During operation, when the controller 1405 issues a command, the motor 1404 drives the transmission shaft 1403 to rotate, which in turn drives the horizontal pulley 1401 and the fixed pulley 1402 to rotate, and finally pulls the pull ring 402 through the rope. With the balancing effect of the counterweight 401 and the guiding effect of the guide rail 404, the porous medium partition 4 can be moved up and down smoothly and accurately.

[0036] The lower part of the heat storage tank 3 is equipped with a heating rod 301 for auxiliary heating during system startup or when sunlight is insufficient, ensuring that the molten salt remains in a liquid state. The upper end of the heat storage tank 3 is equipped with a hot molten salt outlet 5, and the lower end is equipped with a cold molten salt inlet 6.

[0037] The system provided by this invention adopts a modular storage and operation mode. The outlet ends of three molten salt storage tanks 9 are connected in parallel to the inlet end of the first heat exchanger 7, and the inlet ends of the three molten salt storage tanks 9 are connected in parallel to the outlet end of the second heat exchanger 8. Specifically, a first salt outlet pipeline 12 is provided between the inlet end of the first heat exchanger 7 and the outlet ends of the three molten salt storage tanks 9. The first salt outlet pipeline 12 includes a main salt outlet pipe 1201 and three branch salt outlet pipes 1202 connected in parallel to the main salt outlet pipe 1201. The main salt outlet pipe 1201 is connected to the inlet end of the first heat exchanger 7, and the three branch salt outlet pipes 1202 are correspondingly connected to the outlet ends of the three molten salt storage tanks 9. A flow regulating valve 10 is provided on the main salt outlet pipe 1201 for regulating the total flow rate. Each branch salt outlet pipe 1202 is provided with a shut-off valve 11 for individually controlling the salt outlet passage of the corresponding molten salt storage tank 9.

[0038] A first salt inlet pipe 13 is provided between the outlet end of the second heat exchanger 8 and the inlet ends of the three molten salt storage tanks 9. The first salt inlet pipe 13 includes a main salt inlet pipe 1301 and three branch salt inlet pipes 1302 connected in parallel to the main salt inlet pipe 1301. The main salt inlet pipe 1301 is connected to the outlet end of the second heat exchanger 8, and the three branch salt inlet pipes 1302 are connected to the inlet ends of the three molten salt storage tanks 9 one by one. Each branch salt inlet pipe 1302 is equipped with a shut-off valve 11 for individually controlling the salt inlet passage of the corresponding molten salt storage tank 9.

[0039] In addition, flow regulating valves 10 are installed on the connecting pipes between the second heat exchanger 8 and the molten salt outlet 5, and on the connecting pipes between the first heat exchanger 7 and the molten salt inlet 6, respectively, to regulate the molten salt flow rate on the salt outlet main pipe 1201 and the salt inlet main pipe 1301.

[0040] The heat storage tank 3, the first heat exchanger 7, the second heat exchanger 8, and all pipes and valves are equipped with heat insulation structures to maintain their temperature above the melting point of molten salt and reduce heat loss.

[0041] During system operation, solar energy irradiates and heats the porous medium baffle 4 inside the heat storage tank 3 through the heat collection component 1. The baffle absorbs heat through volume and transfers it to the solid molten salt, causing it to melt. The molten liquid salt flows out through the molten salt outlet 5, and after heat exchange in the second heat exchanger 8, it becomes cold molten salt. After preheating in the first heat exchanger 7, it flows back to the bottom of the heat storage tank 3 through the molten salt inlet 6. Simultaneously, molten salt can be stored or replenished through the first salt outlet pipe 12, the first salt inlet pipe 13, and various valves, achieving modular operation of the system. The controller 1405 can control the drive mechanism to adjust the position of the porous medium baffle 4 according to the liquid level or melting process.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A modular molten salt thermal storage system based on volumetric absorption, characterized in that, The device includes a heat collection component, a heat storage tank, a porous medium baffle, a drive mechanism, at least two molten salt storage tanks, a first heat exchanger, a second heat exchanger, and connecting pipelines. The heat collection component is located on the upper part of the heat storage tank. The porous medium baffle is located inside the heat storage tank and is configured to move vertically under the drive of the drive mechanism. A heating rod is provided at the lower part of the heat storage tank, and a molten salt outlet is provided at the upper end of the heat storage tank, while a molten salt inlet is provided at the lower end. The outlet end of the molten salt storage tank is connected to the molten salt inlet of the heat storage tank through the first heat exchanger, and the molten salt outlet of the heat storage tank is connected to the inlet end of the molten salt storage tank through the second heat exchanger, forming a molten salt circulation loop. The porous medium partition includes a partition body and an absorption-heat conduction structure filled inside it. The absorption-heat conduction structure includes an upper absorption part and a lower heat conduction part. The upper absorption part is made of black foamed silicon carbide porous medium, and the lower heat conduction part is made of foamed copper porous medium.

2. The modular molten salt thermal storage system based on volumetric absorption according to claim 1, characterized in that, The drive mechanism includes a pull ring, a rope, a vertical pulley, a horizontal pulley, a fixed pulley, a drive shaft, a motor, and a controller; the pull ring is fixedly connected to the porous medium partition; the vertical and horizontal pulleys are located at the top of the inner wall of the heat storage tank; one end of the rope is connected to the pull ring, and the other end passes through the vertical and horizontal pulleys in sequence, and then winds around the drive shaft through the fixed pulley; the drive shaft is connected to the output shaft of the motor, and the motor is electrically connected to the controller.

3. The modular molten salt thermal storage system based on volumetric absorption according to claim 2, characterized in that, The driving mechanism also includes a guide rail, which is vertically disposed on the inner wall of the heat storage tank. The edge of the porous medium partition is provided with a sliding groove that matches the guide rail, and the porous medium partition slides along the guide rail.

4. The modular molten salt thermal storage system based on volumetric absorption according to claim 2, characterized in that, The drive mechanism also includes a counterweight block, which is disposed above the porous medium partition.

5. The modular molten salt thermal storage system based on volumetric absorption according to claim 1, characterized in that, The porous medium partition is covered with a heat-insulating material.

6. The modular molten salt thermal storage system based on volumetric absorption according to claim 1, characterized in that, The number of molten salt storage tanks is three; the outlets of the three molten salt storage tanks are connected in parallel and then connected to the inlet of the first heat exchanger, and the inlet of the three molten salt storage tanks are connected in parallel and then connected to the outlet of the second heat exchanger.

7. The modular molten salt thermal storage system based on volumetric absorption according to claim 1, characterized in that, The connecting pipeline includes a first salt outlet pipeline and a first salt inlet pipeline; The first salt outlet pipeline includes a main salt outlet pipe and several branch salt outlet pipes connected in parallel to the main salt outlet pipe. The main salt outlet pipe is connected to the inlet end of the first heat exchanger, and each branch salt outlet pipe is connected to the outlet end of a molten salt storage tank. The main salt outlet pipe is equipped with a flow regulating valve, and each branch salt outlet pipe is equipped with a shut-off valve. The first salt inlet pipeline includes a main salt inlet pipe and several branch salt inlet pipes connected in parallel to the main salt inlet pipe. The main salt inlet pipe is connected to the outlet end of the second heat exchanger, and each branch salt inlet pipe is connected to the inlet end of a molten salt storage tank. Each branch salt inlet pipe is equipped with a shut-off valve.

8. The modular molten salt thermal storage system based on volumetric absorption according to claim 1, characterized in that, The heat storage tank, the first heat exchanger, the second heat exchanger, and each connecting pipeline are all provided with an external heat insulation structure.

9. The modular molten salt thermal storage system based on volumetric absorption according to claim 1, characterized in that, The heating rod is an electric heating rod.

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