A molten salt tank foundation heat dissipation system and a heat dissipation method

Abstract

The application discloses a molten salt tank foundation heat dissipation system and a heat dissipation method, and belongs to the technical field of solar thermal power generation. The heat dissipation system comprises a heat dissipation pipe buried in a molten salt tank foundation, the bottom of the heat dissipation pipe is provided with an upward slope from the middle to both ends, both ends of the heat dissipation pipe are connected with a first rising pipe and a second rising pipe respectively, the first rising pipe and the second rising pipe are partially exposed to the environment, the heat dissipation pipe, the first rising pipe and the second rising pipe form a closed pipeline, and the heat dissipation pipe is filled with a cooling liquid with a boiling point of 60-70 DEG C. The application utilizes the latent heat of phase change of the low-boiling-point cooling liquid to absorb the heat of the tank foundation, the cooling liquid is vaporized by absorbing heat in the heat dissipation pipe, the bubbles move to the rising pipe along the slope, are condensed and release heat in the rising pipe, and the condensed liquid returns to the heat dissipation pipe by gravity, thereby forming a natural circulation and stably controlling the temperature of the tank foundation near the boiling point of the cooling liquid. The application does not need power equipment such as a fan, has the advantages of zero energy consumption, accurate temperature control, uniform temperature field, simple structure, high reliability and the like, and can effectively overcome the problems of high energy consumption, unstable temperature control and large maintenance amount of the existing forced ventilation heat dissipation scheme.

Description

Technical Field

[0001] This invention relates to the field of solar thermal power generation technology, and in particular to a molten salt tank foundation heat dissipation system and heat dissipation method. Background Technology

[0002] Molten salt storage tank foundations are typically constructed of concrete. When the foundation temperature is too high, the concrete may experience thermal expansion, decreased strength, or even thermal cracking, affecting the foundation's load-bearing capacity and structural stability. Simultaneously, excessively high temperatures accelerate the aging of insulation materials, reducing their effectiveness. Furthermore, uneven foundation temperature distribution or overheating can lead to uneven settlement at the tank bottom, increasing the risk of leakage. Therefore, controlling the tank foundation temperature within a reasonable range (usually not exceeding 70°C) is crucial for ensuring the safe and stable operation of molten salt storage tanks.

[0003] Currently, most high-temperature molten salt storage tank foundations adopt a forced ventilation and heat dissipation scheme, which involves pre-embedding ventilation pipes in the foundation and using fans to remove heat from the foundation through intermittent or continuous operation, thereby controlling the tank foundation temperature to not exceed 70°C.

[0004] The existing solution has the following main drawbacks: 1. High energy consumption: Wind turbines need to operate continuously or intermittently, consuming a large amount of electricity, which increases the power plant's power consumption rate and operating costs.

[0005] 2. Unstable temperature control: Temperature control using a fan start-stop system can easily lead to large fluctuations in the base temperature, making it difficult to achieve precise constant temperature control and affecting the thermal stability of the tank foundation.

[0006] 3. Uneven temperature distribution: Forced ventilation can easily create localized overheated or undercooled areas inside the foundation, resulting in an uneven temperature field distribution. This can lead to uneven settlement of the tank foundation and increase the risk of tank leakage.

[0007] 4. Poor environmental adaptability: In areas with high ambient temperature or poor heat dissipation conditions, relying solely on air cooling is insufficient to meet heat dissipation requirements, which may lead to overheating of the base.

[0008] 5. High equipment maintenance workload: Moving parts such as fans and valves require regular inspection and maintenance, which increases operation and maintenance costs and system failure points.

[0009] Therefore, there is an urgent need for a heat dissipation solution for molten salt tanks that is energy-efficient, has stable temperature control, uniform temperature field, strong environmental adaptability, and is easy to maintain. Summary of the Invention

[0010] To address the aforementioned technical problems, this invention provides a molten salt tank foundation heat dissipation system and method, aiming to achieve low energy consumption operation, precise and stable temperature control, uniform foundation temperature field distribution, strong environmental adaptability, simple structure, and maintenance-free operation.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows: A molten salt tank foundation heat dissipation system includes a heat dissipation pipe buried in the foundation of the molten salt tank. The bottom of the heat dissipation pipe is sloped upward from the middle to both ends. The two ends of the heat dissipation pipe are respectively connected to a first riser pipe and a second riser pipe. Both the first riser pipe and the second riser pipe are partially exposed to the environment. The heat dissipation pipe, the first riser pipe and the second riser pipe form a closed pipeline. The heat dissipation pipe is filled with a coolant with a boiling point of 60-70℃.

[0012] Preferably, the coolant is HFE-7100.

[0013] Preferably, the slope of the heat dissipation pipe is 0.5‰-5‰.

[0014] In a further technical solution, the outer walls of the first riser and the second riser are provided with a heat exchange enhancement structure.

[0015] Preferably, the enhanced heat exchange structure is a fin, a heat sink, or a heat exchange plate.

[0016] In the above scheme, the foundation of the molten salt tank includes, from bottom to top, a layer of ceramsite or calcium silicate board, a layer of C20 concrete, a layer of insulating bricks and a layer of C40 concrete, and the heat dissipation pipe is embedded in the C20 concrete layer.

[0017] In the above scheme, the heat dissipation pipe includes multiple heat dissipation pipes, which are arranged in parallel.

[0018] In a further technical solution, the two ends of multiple heat dissipation pipes are connected to a first main pipe via a first riser pipe and to a second main pipe via a second riser pipe. The first and second main pipes are filled with coolant with a boiling point of 60-70℃, and the liquid level is kept at the same level.

[0019] In a further technical solution, the first main pipe and the second main pipe are arranged along the edge of the molten salt tank foundation.

[0020] A method for heat dissipation of a molten salt tank foundation, employing a molten salt tank foundation heat dissipation system as described above, includes the following process: (1) A sloping heat dissipation pipe is buried in the foundation of the molten salt tank, and a first riser pipe and a second riser pipe are connected to its two ends; the first riser pipe and the second riser pipe are partially exposed to the environment. (2) Fill the closed pipeline formed by the heat dissipation pipe, the first riser pipe and the second riser pipe with a boiling point of 60-70℃; (3) The coolant in the heat dissipation pipe absorbs the heat at the bottom of the molten salt tank, causing it to vaporize and form bubbles; (4) The bubble moves along the upwardly inclined heat dissipation pipe to the first and second riser pipes at both ends; (5) The bubbles exchange heat with the ambient air in the first and second riser pipes and condense into liquid; (6) The condensed liquid coolant flows back to the heat dissipation pipe under the action of gravity, forming a natural circulation, so as to maintain the temperature of the molten salt tank base near the boiling point of the coolant.

[0021] Through the above technical solution, the molten salt tank basic heat dissipation system and heat dissipation method provided by the present invention have the following beneficial effects: 1. Zero-energy operation: Utilizing the latent heat of vaporization of low-boiling-point coolant to absorb the base heat of the tank, it eliminates the need for power equipment such as fans, consumes no electricity, achieves passive heat dissipation, and significantly reduces the power plant's power consumption rate and operating costs.

[0022] 2. Precise and stable temperature control: By utilizing the gas-liquid two-phase equilibrium characteristics of coolant at its boiling point, the tank base temperature is stably maintained near the boiling point of the coolant, with small temperature fluctuations and high temperature control accuracy, effectively avoiding the problem of frequent temperature fluctuations in forced ventilation schemes.

[0023] 3. Uniform temperature field distribution: The heat dissipation pipes are evenly arranged within the foundation. By utilizing the high efficiency and self-balancing characteristics of phase change heat transfer, local hot spots can be effectively eliminated, achieving a uniform distribution of the foundation temperature field. This reduces the risk of uneven settlement caused by uneven temperature and improves the operational safety of the storage tank.

[0024] 4. High safety: It uses non-flammable, low-toxic, and environmentally friendly working fluids such as HFE-7100 with ODP of 0. It is safe and reliable to operate in high-temperature environments, with no fire hazards and is environmentally friendly.

[0025] 5. Simple structure and high reliability: The system has no moving parts, avoiding the risk of failure of moving equipment such as fans and valves, resulting in low maintenance costs and long service life.

[0026] 6. Strong environmental adaptability: The heat dissipation capacity mainly relies on the latent heat of phase change of the working fluid, which is less affected by the ambient temperature. It can still maintain stable heat dissipation performance in high-temperature areas or in scenarios with poor heat dissipation conditions, and has a wide range of applications.

[0027] In summary, this invention effectively overcomes the problems of high energy consumption, unstable temperature control, uneven temperature distribution, and large maintenance requirements of existing forced ventilation cooling solutions, and provides a highly efficient, stable, and reliable passive cooling solution. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0029] Figure 1This is a basic structural diagram of the molten salt tank in Embodiment 1 of the present invention; Figure 2 This is a three-dimensional schematic diagram of the arrangement of the heat dissipation pipes in the molten salt tank foundation in Embodiment 1 of the present invention; Figure 3 This is a side view of the heat dissipation pipe arrangement of the molten salt tank foundation in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the structure of the heat dissipation pipe of the molten salt tank in Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the heat dissipation system of the molten salt tank foundation using a mother tube structure in Embodiment 2 of the present invention.

[0030] In the diagram: 1. Tank top; 2. Insulation cotton; 3. Tank wall; 4. Tank bottom; 5. Fine sand cushion layer; 6. C40 concrete layer; 7. Insulation bricks; 8. Steel plate ring; 9. Heat dissipation pipe; 9a. Bottom of heat dissipation pipe; 9b. First riser pipe; 9c. Second riser pipe; 9d, 9e. Enhanced heat exchange structure; 9f. First main pipe; 9g. Second main pipe; 10. Lightweight aggregate concrete partition wall; 11. Soil; 12. C20 concrete layer; 13. Lightweight aggregate or calcium silicate board layer. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0032] Example 1 This embodiment provides a molten salt tank foundation heat dissipation system, which includes a molten salt tank structure and a liquid heat dissipation circulation system embedded in the foundation.

[0033] like Figure 1 As shown, the molten salt tank structure includes a tank top 1, insulation cotton 2, tank wall 3, and tank bottom 4. The insulation cotton 2 covers the outside of the tank top 1 and tank wall 3, serving as thermal insulation; the tank bottom 4 is in direct contact with the foundation and is used to transfer the load of the tank body and molten salt.

[0034] like Figures 1 to 3 As shown, the basic layered structure, from the bottom 4 of the tank downwards, consists of a fine sand cushion layer 5, a C40 concrete layer 6, insulating bricks 7, a steel plate ring 8, a C20 concrete layer 12, and a layer of expanded clay or calcium silicate board 13. The insulating bricks 7 are placed below the C40 concrete layer 6 and serve as insulation; the steel plate ring 8 surrounds the insulating bricks 7 and provides structural reinforcement and restraint; the C20 concrete layer 12 serves as the bottom layer of concrete, providing load-bearing and leveling; and the expanded clay or calcium silicate board layer 13 serves as the insulation layer of the tank foundation, preventing heat from diffusing into the deeper soil layers.

[0035] like Figure 4As shown, the liquid cooling circulation system includes a cooling pipe 9, a first riser pipe 9b, and a second riser pipe 9c. The cooling pipe 9 is embedded in the C20 concrete layer 12, located between the insulation brick 7 and the C20 concrete layer 12. The cooling pipe 9 is inclined upwards from its bottom 9a to both ends, with a preferred slope of 1‰. One end of the cooling pipe 9 is connected to the first riser pipe 9b, and the other end is connected to the second riser pipe 9c. The first riser pipe 9b and the second riser pipe 9c extend upwards out of the ground, at least partially exposed to the ambient air. The cooling pipe 9, the first riser pipe 9b, and the second riser pipe 9c form a closed pipeline filled with a low-boiling-point coolant. The boiling point of the coolant is configured to be lower than or equal to the maximum allowable operating temperature (70°C) of the molten salt tank foundation. The coolant cannot fill the entire closed pipeline; space needs to be reserved for vaporization. In this embodiment, the coolant selected is HFE-7100, which has a boiling point of approximately 60°C and is non-flammable, low-toxic, and has an ODP of 0.

[0036] To further improve heat dissipation efficiency, this embodiment provides enhanced heat exchange structures 9d and 9e on the outer walls of the first riser 9b and the second riser 9c. These enhanced heat exchange structures can be fins, ribs, or heat sinks, used to increase the heat exchange area and improve the convective heat transfer coefficient with ambient air.

[0037] The working principle of the molten salt tank foundation heat dissipation system in this embodiment is as follows: During operation of the molten salt tank, heat from the bottom 4 is transferred downwards through the fine sand layer 5, C40 concrete layer 6, and insulating bricks 7 to the C20 concrete layer 12. The low-boiling-point coolant in the heat dissipation pipe 9 absorbs this heat, raising its temperature to its boiling point (approximately 60°C), undergoing a phase change and vaporizing to form bubbles. Due to the upward slope at both ends of the bottom 9a of the heat dissipation pipe 9, the bubbles move upwards along the pipe under buoyancy, entering the first riser pipe 9b and the second riser pipe 9c. After carrying heat into the riser pipes, the bubbles are exposed to the ambient air, exchanging heat with the environment. Upon encountering cold air, the bubbles liquefy, releasing latent heat of vaporization and forming condensate droplets. Under gravity, the condensate flows downwards along the inner wall of the riser pipes, re-collecting at the bottom 9a of the heat dissipation pipe to replenish the evaporated liquid. The above process continues, forming a natural cycle of "heat absorption - vaporization - migration - condensation - reflux". Since the coolant maintains a gas-liquid two-phase equilibrium at the boiling point temperature, the tank base temperature is stably controlled near the boiling point of the coolant (about 60°C), achieving constant temperature heat dissipation.

[0038] Example 2 This embodiment is a simplified and improved version of Embodiment 1, and is suitable for large-diameter storage tanks or scenarios with high requirements for manufacturing costs.

[0039] like Figure 5As shown, in this embodiment, multiple heat dissipation pipes 9 are arranged in parallel. One end of each heat dissipation pipe 9 is connected to a first main pipe 9f via a first riser pipe 9b, and the other end of each heat dissipation pipe 9 is connected to a second main pipe 9g via a second riser pipe 9c. The first main pipe 9f and the second main pipe 9g are arranged along the edge of the molten salt tank foundation, and are filled with low-boiling-point coolant, with their liquid levels configured to be flush.

[0040] This embodiment eliminates the finned heat exchange structures on the outer walls of each riser pipe, utilizing the large heat exchange area of ​​the main pipe itself and the thermal inertia of the stored liquid to achieve heat dissipation. The liquid levels on both main pipes are flush, automatically balancing the working fluid distribution using the principle of communicating vessels, maintaining uniform liquid supply to each heat dissipation pipe without additional control. This embodiment significantly simplifies the structure and reduces manufacturing costs, while retaining the core principle of passive phase change cooling, exhibiting excellent self-balancing characteristics and engineering adaptability. Using two main pipes to complete the condensation and liquid storage functions reduces the number of pipes and wall penetrations, lowering material and construction costs; the main pipes provide a larger flow cross-section and working fluid storage capacity, preventing bubble accumulation and blockage, and exhibiting strong resistance to thermal load disturbances.

[0041] A method for heat dissipation of a molten salt tank foundation, the method employing the molten salt tank foundation heat dissipation system as described in Example 1 or Example 2, specifically including the following steps: (1) A sloping heat dissipation pipe is buried in the foundation of the molten salt tank and a first riser pipe and a second riser pipe are connected at both ends, exposing at least a portion of the first riser pipe and the second riser pipe to the environment. (2) Fill the closed pipeline formed by the heat dissipation pipe, the first riser pipe and the second riser pipe with a boiling point of 60-70℃; (3) The coolant in the heat dissipation pipe absorbs the heat at the bottom of the molten salt tank, causing it to vaporize and form bubbles; (4) Move the bubble along the upwardly inclined heat dissipation pipe to the first and second riser pipes at both ends; (5) Allow the bubbles to exchange heat with the ambient air in the first and second riser pipes and condense into liquid; (6) The condensed liquid coolant flows back to the heat dissipation pipe under the action of gravity, forming a natural circulation, so as to maintain the temperature of the molten salt tank base near the boiling point of the coolant.

[0042] The above method achieves passive constant temperature heat dissipation of the molten salt tank foundation, requiring no external power, with precise temperature control and uniform temperature field distribution.

[0043] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A molten salt tank foundation heat dissipation system, characterized in that, The device includes a heat dissipation pipe embedded in the foundation of a molten salt tank. The bottom of the heat dissipation pipe has an upward slope from the middle to both ends. The two ends of the heat dissipation pipe are respectively connected to a first riser pipe and a second riser pipe. Both the first riser pipe and the second riser pipe are partially exposed to the environment. The heat dissipation pipe, the first riser pipe, and the second riser pipe form a closed pipeline. The heat dissipation pipe is filled with a coolant with a boiling point of 60-70℃.

2. The molten salt tank foundation heat dissipation system according to claim 1, characterized in that, The coolant is HFE-7100.

3. The molten salt tank foundation heat dissipation system according to claim 1, characterized in that, The slope of the heat dissipation pipe is 0.5‰-5‰.

4. The molten salt tank foundation heat dissipation system according to claim 1, characterized in that, The outer walls of the first and second riser pipes are provided with enhanced heat exchange structures.

5. A molten salt tank foundation heat dissipation system according to claim 4, characterized in that, The enhanced heat exchange structure is a fin, a rib, or a heat sink.

6. A molten salt tank foundation heat dissipation system according to claim 1, characterized in that, The foundation of the molten salt tank includes, from bottom to top, a layer of ceramsite or calcium silicate board, a layer of C20 concrete, a layer of insulating bricks, and a layer of C40 concrete, with the heat dissipation pipe embedded in the C20 concrete layer.

7. A molten salt tank foundation heat dissipation system according to claim 1, characterized in that, The heat dissipation pipes include multiple pipes, which are arranged in parallel.

8. A molten salt tank foundation heat dissipation system according to claim 7, characterized in that, Multiple heat dissipation pipes are connected to the first main pipe at both ends via the first riser pipe and to the second main pipe via the second riser pipe. The first and second main pipes are filled with coolant with a boiling point of 60-70℃, and the liquid level is kept at the same level.

9. A molten salt tank foundation heat dissipation system according to claim 7, characterized in that, The first and second main pipes are arranged along the edge of the molten salt tank foundation.

10. A method for heat dissipation of a molten salt tank foundation, employing a molten salt tank foundation heat dissipation system as described in any one of claims 1-9, characterized in that, The process includes the following: (1) A sloping heat dissipation pipe is buried in the foundation of the molten salt tank, and a first riser pipe and a second riser pipe are connected to its two ends; the first riser pipe and the second riser pipe are partially exposed to the environment. (2) Fill the closed pipeline formed by the heat dissipation pipe, the first riser pipe and the second riser pipe with a boiling point of 60-70℃; (3) The coolant in the heat dissipation pipe absorbs the heat at the bottom of the molten salt tank, causing it to vaporize and form bubbles; (4) The bubble moves along the upwardly inclined heat dissipation pipe to the first and second riser pipes at both ends; (5) The bubbles exchange heat with the ambient air in the first and second riser pipes and condense into liquid; (6) The condensed liquid coolant flows back to the heat dissipation pipe under the action of gravity, forming a natural circulation, so as to maintain the temperature of the molten salt tank base near the boiling point of the coolant.

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