Single-tank integrated molten salt heat storage system

Abstract

The invention relates to the technical field of fused salt heat energy storage, in particular to a single-tank integrated fused salt heat storage system which comprises a tank body, a confluence outlet is formed in the tank body, the interior of the tank body is divided into a plurality of heating subareas in the circumferential direction, and heat exchange pipe sets are arranged in the heating subareas and used for fluid circulation. A traditional fused salt storage tank needs to be provided with accessories such as electric heat tracing, and construction and operation cost is high; on the basis of a traditional integrated heat storage device, a molten salt heat exchange pipeline is reasonably arranged, an external heat source is used for dissolving salt, input of electric heat tracing equipment is avoided, uniform melting of the molten salt in the storage tank is achieved, and the storage tank is high in heat exchange efficiency and low in energy consumption. And the heat utilization efficiency and the overall economical efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of molten salt thermal energy storage, and in particular to a single-tank integrated molten salt thermal storage system. Background Art

[0002] High-temperature molten salt thermal storage systems can be categorized as single-tank or dual-tank systems based on their application. Dual-tank systems typically require two separate tanks to store high-temperature and low-temperature molten salts, resulting in relatively high floor space and facility costs. Single-tank systems, on the other hand, store both hot and cold salts in the same tank, reducing the total investment footprint of the thermal storage system. However, single-tank systems can encounter issues such as difficulty controlling the thermocline layer and excessive heat loss caused by the mixing of hot and cold salts.

[0003] Integrated molten salt systems can further enhance the integration of thermal storage systems. This involves placing an immersed heat exchanger within a single tank. During heat storage, high-temperature fluid flows into the heat exchanger to heat the thermal storage medium within the tank. During heat release, the thermal storage medium flows through the heat exchanger to extract heat.

[0004] Commonly used molten salts, such as binary and ternary salts, typically have freezing points between 120°C and 240°C, significantly higher than the ambient temperature. To ensure the molten salt flows properly as a liquid within the pipeline, a series of insulation measures are typically required. A common insulation solution involves installing electric heating devices on the outer surface of the molten salt pipeline. However, traditional molten salt storage tanks require electric heating and associated accessories, requiring continuous power input during operation, resulting in high initial investment and operating costs.

[0005] Despite this, under extreme conditions, such as insufficient sunlight or system downtime, excessive heat loss can still lead to partial or even complete freezing of the molten salt pipes. Therefore, in integrated molten salt thermal storage systems, solving the problem of salt dissolution after freezing becomes a key process.

[0006] If the tank is filled with solid molten salt during a freeze-blocking event, proper salt dissolution methods are necessary to thaw the tank. Generally, molten salt expands as it transitions from solid to liquid, a major cause of salt leaks. This expansion during thawing can cause significant deformation and bending of the tank wall. Studies have shown that permanent deformation of the tank wall can reach 4% or more. Stress concentration during salt dissolution can easily cause stress in stress-concentrated areas of the tank wall, leading to salt leaks. Frequent alternations of hot and cold temperatures can also impact the lifespan of the tank metal. Welds and external connections are generally the most susceptible to salt leaks in a tank. During thawing, if the solid salt in the center melts first, it generates an outward thrust. Uneven salt dissolution can transfer this expansion thrust to the tank wall, causing stress concentrations that can ultimately lead to salt leaks. Summary of the Invention

[0007] In response to the technical problems that traditional molten salt storage tanks need to be equipped with accessories such as electric heating, which results in high construction and operating costs; and the molten salt easily causes stress concentration on the tank wall during salt melting, the present invention provides a single-tank integrated molten salt thermal storage system. Based on the traditional integrated thermal storage device, it rationally arranges the molten salt heat exchange pipeline, utilizes an external heat source to melt the salt, avoids the investment in electric heating equipment, realizes uniform melting of the molten salt in the storage tank, and improves heat utilization efficiency and overall economy.

[0008] The technical solution provided by the present invention is: a single-tank integrated molten salt heat storage system, comprising a tank body, the tank body being provided with a confluence outlet, the tank body being divided into a plurality of heating zones along the circumferential direction, the heating zones being provided with a heat exchange tube group, the heat exchange tube group being used for circulating a fluid; the heat exchange tube group comprising an inlet pipe, an outlet pipe, a transverse pipe, and n layers of longitudinal pipe networks continuously arranged from near the tank wall toward the center of the tank body; the inlet pipe is connected to a fluid heat source through a control valve body, and the inlet pipes of each heat exchange tube group are connected in parallel, the outlet pipe is located in the central area of ​​the tank body, and the outlet pipe is connected to the confluence outlet; the longitudinal pipe networks are connected by transverse pipes, and the inlet pipes and transverse pipes connected to the same layer of longitudinal pipe networks, the transverse pipes connected to the same layer of longitudinal pipe networks, and the transverse pipes and outlet pipes connected to the same layer of longitudinal pipe networks are all staggered so that the fluid traverses each layer of longitudinal pipe networks when flowing from the inlet pipe to the outlet pipe.

[0009] Optionally, the longitudinal pipe network includes several longitudinal pipes and connecting pipes, the longitudinal pipes are connected by the connecting pipes, and several spiral fins are arranged at intervals on the outer walls of the longitudinal pipes and the transverse pipes, and the spiral fins are fixedly connected to the longitudinal pipes and the transverse pipes.

[0010] Optionally, the extended width of the spiral fin gradually decreases along the spiral direction so that the spiral fin is conical; the cone tip of the spiral fin located on the longitudinal pipe faces upward; the cone tip of the spiral fin located on the transverse pipe faces toward the center of the tank body.

[0011] Optionally, the thickness of the spiral fin is 2-4 mm, and the extended width of the spiral fin decreases gradually from 4-6 mm at the cone bottom to 0 mm toward the cone tip.

[0012] Optionally, the spiral fins are filled with phase change material.

[0013] Optionally, the spiral fin has a helical pitch angle of 25-35°.

[0014] Optionally, the spacing between adjacent spiral fins is 25-35 mm.

[0015] Optionally, each heating zone of the tank body is provided with a temperature sensor, a pressure sensor and a displacement sensor, and also includes a data acquisition and processing unit and a controller; the temperature sensor, pressure sensor and displacement sensor are electrically connected to the data acquisition and processing unit, and the data acquisition and processing unit and the control valve body are electrically connected to the controller.

[0016] The technical solution provided by the present invention has the following beneficial effects compared with the existing technology: in view of the technical problem that traditional molten salt storage tanks need to be equipped with accessories such as electric heating, which has high construction and operation costs; and the molten salt easily causes stress concentration on the tank wall during salt melting, the present invention, based on the traditional integrated heat storage device, rationally arranges the molten salt heat exchange pipeline, uses an external heat source to melt the salt, avoids the investment in electric heating equipment, realizes uniform melting of the molten salt in the storage tank, and improves the heat utilization efficiency and overall economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is one of the structural schematic diagrams of the single-tank integrated molten salt thermal storage system proposed in an embodiment of the present invention.

[0018] Figure 2 This is the second structural schematic diagram of the single-tank integrated molten salt thermal storage system proposed in an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the layout of the spiral fins proposed in an embodiment of the present invention.

[0020] Figure 4 This is a partial cross-sectional schematic diagram of the spiral fin proposed in an embodiment of the present invention.

[0021] Figure 5 This is the third structural schematic diagram of the single-tank integrated molten salt thermal storage system proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to further understand the content of the present invention, the present invention is described in detail with reference to the accompanying drawings and embodiments.

[0023] The present application will be further described below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended solely to illustrate the relevant inventions and are not intended to limit the inventions. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the drawings. Terms such as "first" and "second" in the present application are provided for the convenience of describing the technical solutions of the present invention and do not have a specific limiting effect. They are general references and do not constitute a limitation on the technical solutions of the present invention. It should be noted that the embodiments and features therein in the present application may be combined with each other unless there is a conflict. In the description of the present invention, it should be noted that terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a communication between the two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not have contradictions or conflicts, all of which are within the scope of protection required by the present invention.

[0024] Combined with attachment Figure 1-5 This embodiment proposes a single-tank integrated molten salt thermal storage system, including a tank body 1, a confluence outlet 2 is provided on the tank body 1, a plurality of heating zones 3 are divided circumferentially in the tank body 1, and a heat exchange tube group 4 is provided in the heating zone 3, and the heat exchange tube group 4 is used for circulating fluid.

[0025] Heat exchange tube group 4 includes an inlet pipe 40, an outlet pipe 41, transverse pipes 42, and n layers of longitudinal pipe network 43 arranged continuously from the wall of tank 1 toward the center of tank 1. The inlet pipe 40 is connected to the fluid heat source via a control valve 7, and the inlet pipes 40 of each heat exchange tube group 4 are connected in parallel. The outlet pipe 41 is located in the center of tank 1 and is connected to the confluence outlet 2.

[0026] The longitudinal pipe networks 43 are connected by transverse pipes 42. The inlet pipes 40 and transverse pipes 42 connected to the longitudinal pipe networks 43 on the same layer, the transverse pipes 42 connected to the longitudinal pipe networks 43 on the same layer, and the transverse pipes 42 and outlet pipes 41 connected to the longitudinal pipe networks 43 on the same layer are all staggered so that the fluid traverses each layer of the longitudinal pipe networks 43 when flowing from the inlet pipe 40 to the outlet pipe 41.

[0027] The single-tank integrated molten salt thermal storage system of this embodiment is intended to solve the following technical problems: (1) Traditional molten salt storage tanks need to be equipped with electric heating and supporting accessories, and continuous power input is required during operation, resulting in high initial equipment investment and operating costs; (2) Stress concentration during salt smelting can easily cause stress in the stress concentration area of ​​the tank wall, causing salt leakage in the tank.

[0028] The single-tank integrated molten salt thermal storage system of this embodiment, through the inlet pipe 40, enables the heat exchange tube group 4 in each heating zone 3 to be connected to the external fluid heat source, so as to synchronously heat the molten salt in each heating zone 3 inside the tank body 1 through the fluid, thereby avoiding the configuration of electric heating and supporting accessories, and the fluid finally flows out through the confluence outlet 2 connected to the outlet pipe 41 of the heat exchange tube group 4. The fluid can generally be high-pressure and high-temperature steam (industrial steam) or other fluid that can provide high temperature, and the external fluid heat source generally refers to an industrial heat source that can heat the fluid, a device or system that generates or transports hot fluid, for example, high-temperature and high-pressure steam can be generated by industrial waste heat for use in the single-tank integrated molten salt thermal storage system of this embodiment. Therefore, since the configuration of electric heating and supporting accessories is avoided, the operation process does not require continuous input of electricity, and the initial investment and operating costs of the equipment can also be relatively low.

[0029] In addition, the single-tank integrated molten salt heat storage system of this embodiment improves the uniformity of molten salt by dividing the tank body 1 into several heating zones 3 along the circumferential direction and arranging a heat exchange tube group 4 different from the prior art in each heating zone 3. Moreover, through the design of this heat exchange structure, the imported heat source (i.e., fluid) can flow from the outside to the inside, thereby solving the aforementioned problem of molten salt freezing and blocking the molten salt, achieving uniform melting of the molten salt in the tank body 1, avoiding stress concentration during salt melting, and improving heat utilization efficiency and overall economy.

[0030] Specifically, for the single-tank integrated molten salt thermal storage system of this embodiment, its working principle is as follows: when the molten salt is reheated after freezing, fluid is introduced into the heat exchange tube group 4 in each heating zone 3 to heat or melt the molten salt in the tank body 1, such as Figure 1The arrows in the figure indicate the flow direction of the fluid, which comes from other heat sources (such as industrial waste heat, industrial steam, etc.). Since the heat exchange tube group 4 includes n layers of longitudinal pipe networks 43 arranged continuously from the tank wall of the tank body 1 toward the center of the tank body 1, the dense arrangement of the heat exchange tube group 4 within the tank body 1 ensures that the molten salt in the tank body 1 is evenly heated during the salt thawing process. This can reduce the amount of molten salt melted in local areas of the tank body 1, which increases its volume and produces excessive expansion stress. For example, this can avoid stress concentration near the tank wall or other areas, which can lead to salt leakage accidents in the welds of the tank body 1 or at the connection between the tank body 1 and the outside during the thawing process.

[0031] Based on the above-mentioned arrangement of the heat exchange tube group 4, the molten salt can be ensured to melt relatively evenly as a whole. However, in practice, since the fluid first flows through the tank body 1 near the wall and then gradually flows toward the center of the tank body 1, this flow mode will still cause the molten salt near the outer wall of the tank body 1 to obtain more heat than the molten salt in the central area, and the melting speed is relatively faster, and the amount of melting is relatively larger.

[0032] The volume of salt expands after melting. In the traditional melting process of molten salt after freezing, part of the molten salt in the center area of ​​the tank body 1 generally melts unevenly first, and the molten salt near the tank wall melts slowly. The volume of the molten salt expands as it melts, thus generating an outward thrust. However, the molten salt cannot flow, which easily forms a large-scale thrust accumulation, causing squeezing of the tank wall and affecting the life of the tank wall.

[0033] In order to further prevent the expansion of the molten salt from squeezing key locations on the wall of the tank body 1 (such as pipes, instrument connections, and welds), this embodiment further improves the longitudinal pipe network 43. The longitudinal pipe network 43 includes a plurality of longitudinal pipes 430 and connecting pipes 431. The longitudinal pipes 430 are connected by connecting pipes 431. A plurality of spiral fins 5 are spaced apart on the outer walls of the longitudinal pipes 430 and the transverse pipes 42. The spiral fins 5 are fixedly connected to the longitudinal pipes 430 and the transverse pipes 42.

[0034] Furthermore, the spiral fin 5 is designed so that the extended width of the spiral fin 5 gradually decreases along the spiral direction so that the spiral fin 5 is conical; the cone tip of the spiral fin 5 located on the longitudinal pipe 430 faces upward; and the cone tip of the spiral fin 5 located on the transverse pipe 42 faces the center direction of the tank body 1.

[0035] Therefore, the design of the spiral fins 5 can make the molten salt flow, avoiding the accumulation of thrust. Specifically, the layout design based on the spiral fins 5 is intended to make the molten salt flow toward the center of the tank body 1. It should be noted that guiding the melted molten salt to flow toward the center of the tank body 1 in this embodiment does not cause the stress concentration problem mentioned above in traditional storage tanks. In addition, the spiral fins 5 are generally made of stainless steel.

[0036] Furthermore, during the pure molten salt melting process, the thermal conductivity between the solid heat exchange tube group 4 and the solid molten salt is poor, and heat tends to accumulate on the surface of the heat exchange tube group 4, resulting in slow melting and uneven heating. This results in low efficiency and a long time to completely melt the molten salt. Therefore, during the molten salt heating process, the provision of spiral fins 5 can improve heat transfer capacity, making the molten salt's heat absorption rate faster and more uniform.

[0037] In this embodiment, although the melted molten salt is guided to flow toward the center of the tank body 1, and the total volume of the molten salt in the tank body 1 will also increase during the melting process, the tank body 1 will have a surplus volume when it is designed, and will not be filled in the height direction. The molten salt can flow into the surplus space, and the volume of the molten salt will become smaller after solidification. After melting again, it will only return to the volume ratio of the design working condition.

[0038] In other words, one way to understand the technical concept of this embodiment is that, through the layout of the heat exchange tube group 4 in the tank body 1, it is ensured that the molten salt has a circulation path with the surplus space in the tank body 1, and this path is from the outside to the inside, which can further heat and melt the molten salt in the central area during the flow process. In short, the layout of the heat exchange tube group 4 can avoid the formation of stress concentration.

[0039] In this embodiment, the molten salt will gradually flow from the wall of the tank body 1 toward the center of the tank body 1 along the spiral fins 5. The power of its flow comes from the density change of the molten salt itself. The density of the molten salt is ρ = 2090-0.636 × T (℃), that is, the density of the molten salt will decrease after being heated, which will generate buoyancy to move upward, that is, it will spontaneously move to a higher place. Moreover, due to the difference in temperature of molten salts with different melting degrees, the molten salt with higher temperature will also spontaneously move upward. The role of the spiral fins 5 in this embodiment is to play a diversion effect. The spiral fins 5 are arranged along the longitudinal pipe 430 and the transverse pipe 42, so that the molten salt can be assisted to flow from bottom to top, from the tank wall near the tank body 1 to the center of the tank body 1.

[0040] In some embodiments, the thickness of the spiral fins 5 is 2-4 mm, preferably 3 mm. The extended width of the spiral fins 5 is 4-6 mm, preferably 5 mm, at the base of the cone and gradually decreases to 0 mm toward the cone tip. The distance between adjacent spiral fins 5 is 25-35 mm, preferably 30 mm. This embodiment can enhance the flow guidance effect of the spiral fins 5 and ensure that the molten salt has sufficient flow space in the spiral fins 5.

[0041] And, in some embodiments, the spiral fin 5 has a spiral rise angle of 25-35°, preferably 30°. In this embodiment, the molten salt can rise evenly along the spiral fin 5. The angle of the spiral fin 5 can achieve the effect of guiding the flow while avoiding increasing the flow resistance.

[0042] In short, the detailed design of the spiral fins 5 is to better guide the molten salt to flow from bottom to top, from the tank wall close to the tank body 1 to the center of the tank body 1, thereby reducing the excessive molten salt expansion stress generated in stress concentration areas such as the tank wall of the tank body 1.

[0043] In a further embodiment, the spiral fins 5 are filled with a phase change material 6, such as a gallium alloy. Using a gallium alloy as the phase change material 6 (with a phase change temperature of approximately 300°C) within the spiral fins 5 allows the phase change material 6 to first absorb heat when a fluid such as steam heats the molten salt. Once it reaches its melting point, it maintains a constant temperature, evenly transferring the absorbed heat to the surrounding molten salt, slowing the expansion of the tank body 1 and extending the service life of the tank body 1. This process slows the rapid rise in the temperature of the molten salt in the tank body 1, alleviating localized thermal expansion. Compared to direct heating, the molten salt temperature rise is more uniform, and the expansion amplitude is controlled.

[0044] When the temperature drops, the phase change material 6 will re-solidify, changing from liquid to solid, releasing the stored heat back to the system, reducing the temperature drop and avoiding damage to the tank wall caused by thermal fatigue caused by rapid alternation of hot and cold.

[0045] In a further embodiment, each heating zone 3 of the tank body 1 is provided with a temperature sensor, a pressure sensor and a displacement sensor, and also includes a data acquisition and processing unit and a controller 8; the temperature sensor, pressure sensor and displacement sensor are electrically connected to the data acquisition and processing unit, and the data acquisition and processing unit and the control valve are electrically connected to the controller 8.

[0046] This further implementation method can monitor the molten salt temperature and the expansion of the stress concentration area inside the tank body 1 in real time, so as to dynamically adjust the heating process to reduce the risk of local overheating and volume expansion, and ensure the safety and stability of the tank body 1 during the molten salt or high-temperature heat storage stage.

[0047] Among them, temperature sensors can be distributed in different positions in the tank body 1, especially in high stress areas such as welds, flanges, and tank walls, for real-time monitoring of local temperature. The pressure sensor is preferably installed on the tank wall of the tank body 1, and can be used to monitor the pressure applied to the storage tank during molten salt expansion, with particular attention paid to high temperature areas and areas where expansion is prone to occur. The displacement sensor can detect the deformation of the tank wall of the tank body 1 and determine the volume expansion in combination with the pressure data. Regarding the data acquisition and processing unit, the data collected by the sensor is transmitted to the central processing unit via a wireless or wired network, and the temperature, pressure and displacement data are processed in real time to analyze the thermal expansion trend. The controller 8 can help the operator judge or predict the critical point of expansion based on the collected sensor data, thereby initiating corresponding regulatory measures.

[0048] One regulatory measure involves a controller 8 connected to the control valve body 7, which can precisely adjust parameters such as fluid flow rate and flow rate within different heating zones 3. This allows for control of the amount and distribution of heat within each heating zone 3, ensuring gradual heating of the molten salt and reducing the risk of localized expansion. For example, if the temperature sensors, pressure sensors, and displacement sensors in a specific area detect excessive temperature or expansion, the controller 8 can adjust the control valve body 7 to prioritize reducing heat input in that area, preventing excessive localized stress.

[0049] In one example, when the tank 1 is in the salting stage, the temperature and pressure sensors monitor that the temperature rate in the weld area is greater than 10°C / min. The controller 8 immediately reduces the steam flow in this area to distribute more heat to other cold areas with lower temperatures.

[0050] Combined with all the above descriptions, it can be seen that the single-tank integrated molten salt heat storage system of this embodiment has many advantages: (1) It uses an external heat source to melt salt, saving electric heating and improving overall economic efficiency; (2) Through the layout design of the heat exchange tube group 4, the form of zoned inflow is adopted, and at the same time, a progressive arrangement method is adopted from the tank wall of the tank body 1 to the center of the tank body 1, which can avoid a large amount of molten salt in the center of the tank body 1 from melting in a short period of time, accumulating excessive expansion stress in a certain area of ​​the tank wall of the tank body 1, causing overheating and expansion at key positions such as the weld of the tank body 1, and uniformly heating or cooling the molten salt can also reduce the frequent alternating hot and cold stress on the wall of the tank body 1; (3) The added spiral fins 5 can guide the flow of molten salt and enhance the molten salt heating effect of the heat exchange tube group 4, which not only improves the local heat exchange performance, but also can uniformly melt salt, and under the same conditions, the equipment is less likely to be damaged; (4) By adding phase change material 6 to the spiral fins 5, the phase change of the material is used to avoid the molten salt temperature rising / falling rate being too fast, reducing the metal material from being subjected to frequent alternating hot and cold stress. (5) The temperature sensors, pressure sensors and displacement sensors in the heat exchange partitions are provided with a data acquisition and processing unit and a controller 8, which can monitor the tank wall temperature and volume expansion of the key positions of the tank body 1 in real time, thereby dynamically adjusting the flow rate of the heat source fluid in each heating partition 3 by manipulating the control valve body 7 to reduce the risk of local overheating and volume expansion, and ensure the safety and stability of the tank body 1 during the molten salt or high-temperature heat storage stage.

[0051] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs structures and embodiments similar to this technical solution without creatively designing them, they shall fall within the scope of protection of the present invention.

Claims

1. A single tank integrated molten salt thermal storage system, characterized in that: The invention comprises a tank body (1), wherein the tank body (1) is provided with a converging outlet (2), wherein the tank body (1) is divided into a plurality of heating zones (3) along the circumferential direction, wherein a heat exchange tube group (4) is provided in the heating zone (3), and wherein the heat exchange tube group (4) is used for circulating a fluid; The heat exchange tube group (4) comprises an inlet pipe (40), an outlet pipe (41), a transverse pipe (42), and n layers of longitudinal pipe networks (43) arranged continuously from the tank wall close to the tank body (1) toward the center of the tank body (1); The inlet pipe (40) is connected to the fluid heat source through a control valve body (7), and the inlet pipes (40) of the heat exchange tube groups (4) are connected in parallel. The outlet pipe (41) is located in the central area of ​​the tank body (1), and the outlet pipe (41) is connected to the converging outlet (2); The longitudinal pipe networks (43) are connected to each other via transverse pipes (42); the inlet pipes (40) and transverse pipes (42) connected to the longitudinal pipe network (43) at the same layer, the transverse pipes (42) connected to the longitudinal pipe network (43) at the same layer, and the transverse pipes (42) and outlet pipes (41) connected to the longitudinal pipe network (43) at the same layer are arranged alternately, so that the fluid traverses each layer of the longitudinal pipe network (43) when flowing from the inlet pipe (40) to the outlet pipe (41).

2. A single tank integrated molten salt thermal storage system according to claim 1, characterized in that: The longitudinal pipe network (43) comprises a plurality of longitudinal pipes (430) and connecting pipes (431), the longitudinal pipes (430) being connected to each other via the connecting pipes (431), a plurality of spiral fins (5) being arranged at intervals on the outer walls of the longitudinal pipes (430) and the transverse pipes (42), and the spiral fins (5) being fixedly connected to the longitudinal pipes (430) and the transverse pipes (42).

3. A single tank integrated molten salt thermal storage system according to claim 2, characterized in that: The extended width of the spiral fin (5) gradually decreases along the spiral direction, so that the spiral fin (5) is conical; the cone tip of the spiral fin (5) located on the longitudinal pipe (430) faces upward; and the cone tip of the spiral fin (5) located on the transverse pipe (42) faces the center direction of the tank body (1).

4. A single tank integrated molten salt thermal storage system according to claim 3, characterized in that: The thickness of the spiral fin (5) is 2-4 mm, and the extended width of the spiral fin (5) is 4-6 mm at the bottom of the cone and gradually decreases to 0 towards the tip of the cone.

5. A single tank integrated molten salt thermal storage system according to claim 2 or 3, characterized in that: The spiral fins (5) are filled with phase change material (6).

6. A single tank integrated molten salt thermal storage system according to claim 2 or 3, characterized in that: The helical angle of the spiral fin (5) is 25-35°.

7. A single tank integrated molten salt thermal storage system according to claim 2 or 3, characterized in that: The spacing between adjacent spiral fins (5) is 25-35 mm.

8. The single-tank integrated molten salt thermal storage system according to claim 1, characterized in that: Each of the heating zones (3) of the tank body (1) is provided with a temperature sensor, a pressure sensor and a displacement sensor, and also includes a data acquisition and processing unit and a controller (8); the temperature sensor, the pressure sensor and the displacement sensor are electrically connected to the data acquisition and processing unit, and the data acquisition and processing unit and the control valve body (7) are electrically connected to the controller (8).

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