Multi-layer variable diameter spiral molten salt heat exchanger

Abstract

This utility model discloses a multi-layer variable diameter spiral molten salt heat exchanger, including a lifting mechanism and a spiral coil assembly. The lifting mechanism drives the spiral coil assembly to move up and down within the molten salt tank. The spiral coil assembly includes a spiral coil, an oil inlet manifold, and an oil outlet manifold. The oil inlet manifold has an oil inlet, and the oil outlet manifold has an oil outlet. The spiral coil is spirally coiled below the oil inlet and oil outlet manifolds. The advantages of this utility model are: it enables direct and controllable heat exchange in the molten salt storage tank, achieving high heat exchange efficiency and a higher system thermal energy utilization rate than traditional molten salt heat exchange systems; the implementation of this equipment system can reduce system investment, resulting in significant advantages in system operation benefits, and it is easily controlled digitally.

Description

Technical Field

[0001] This utility model relates to the field of heat exchange technology in liquid heat medium with poor heat convection, and in particular to a multi-layer variable diameter spiral molten salt heat exchange device, which is specifically designed for the heat exchange system between molten salt and heat transfer oil, and involves a device that can precisely adjust the heat exchange area according to the heat exchange efficiency and the temperature range of the molten salt. Background Technology

[0002] In new energy fields such as solar thermal power generation and industrial waste heat utilization, the heat exchange system between molten salt and heat transfer oil is the core link in energy transfer. Because molten salt has high-temperature phase change characteristics (typically operating in the 220–550℃ range), while the upper limit of heat transfer oil's operating temperature is generally below 400℃, a significant temperature gradient and abrupt change in heat exchange efficiency exist between the two media. Although traditional fixed-structure shell-and-tube heat exchangers can meet basic heat exchange requirements, they reveal the following key defects in actual operation:

[0003] 1. Efficiency fluctuations caused by heat exchange area solidification: When the molten salt is in the high-temperature range (e.g., >400℃), an excessively large contact area can easily lead to local overheating and decomposition of the heat transfer oil; while in the medium-low temperature range (e.g., 280~350℃), a fixed heat exchange area cannot meet the heat power demand, causing a sharp drop in system efficiency of more than 30%. Although existing technologies use multi-stage valve diversion to adjust the flow rate, they cannot change the fundamental parameter of effective heat exchange area.

[0004] 2. Laminar boundary layer accumulation problem: Molten salts tend to form a stable laminar boundary layer in conventional spiral coils, and the thermal resistance increases by 2 to 3 times compared with the turbulent state.

[0005] 3. Insufficient reliability of mechanical adjustment: Although the hydraulic lifting adjustment device can change the immersion depth of the tube bundle, there are two major technical bottlenecks: ① The lifting stroke and the heat exchange area have a non-linear relationship, making it difficult to achieve precise control in the critical temperature range (such as 320±10℃); ② The synchronous lifting of the multi-layer tube bundle generates fluid impact vibration, which accelerates the failure of the sealing structure.

[0006] 4. Existing molten salt and thermal oil heat exchangers mostly employ bidirectional flow of molten salt and thermal oil for heat exchange (shell side and tube side), maintaining a constant heat exchange area and controlling the flow rate to achieve temperature control. Such devices require molten salt pumps, molten salt circulation systems, and dedicated heat exchangers, resulting in high costs, high operating and maintenance expenses, and limited market application. Therefore, there is an urgent need to develop an adaptive heat exchanger that can match the molten salt temperature-viscosity characteristic curve in real time, achieving efficiency optimization under all operating conditions through precise adjustment of the effective heat exchange area, while simultaneously addressing the reliability issues of traditional mechanical adjustment mechanisms. Utility Model Content

[0007] The purpose of this invention is to solve the problems of the prior art and provide a multi-layer variable diameter spiral molten salt heat exchanger.

[0008] The objective of this utility model is achieved through the following technical solution: a multi-layer variable diameter spiral molten salt heat exchanger, comprising a lifting mechanism and a spiral coil assembly; the lifting mechanism drives the spiral coil assembly to rise and fall within the molten salt tank; the spiral coil assembly includes a spiral coil, an oil inlet manifold, and an oil outlet manifold; the oil inlet manifold is provided with an oil inlet; the oil outlet manifold is provided with an oil outlet; the spiral coil is spirally coiled below the oil inlet manifold and the oil outlet manifold;

[0009] The spiral coil, along the direction of heat transfer oil flow, includes, in sequence, an inlet end, a downcomer pipe, a spiral riser pipe, and an oil outlet pipe; the inlet end is located at the top of the spiral coil and is connected to the oil inlet manifold; the downcomer pipe extends downward from the inlet end to the bottom of the spiral coil; the spiral riser pipe spirals upward from the end of the downcomer pipe to the top of the spiral coil; the end of the spiral riser pipe is connected to the oil outlet pipe; and the oil outlet pipe is connected to the oil outlet manifold.

[0010] Fins are welded to the surface of the spiral coil; the fins connect two adjacent spiral rising pipes in the upper and lower layers.

[0011] The vertical spacing between adjacent spiral riser pipes in the upper and lower layers is 10-15cm;

[0012] The spiral coil assembly includes at least two spiral coils; when the number of spiral coils is ≥2, the central axes of each spiral coil coincide, and the outer diameter of each spiral coil increases sequentially from the central axis outward.

[0013] The minimum outer diameter of the innermost spiral coil is 40 cm; the maximum outer diameter is determined by the inner diameter of the molten salt vessel.

[0014] A further technical solution is that the lifting mechanism includes a lifting motor, a transmission device, a lifting screw, a lifting connecting rod, and a mounting frame. The lifting motor drives the lifting screw to move up and down through the transmission device. The lifting screw extends into the molten salt tank and is connected to the mounting frame through the lifting connecting rod. The mounting frame is fixedly connected to the oil inlet manifold and the oil outlet manifold. In this utility model, the lifting motor and transmission device can adopt a conventional mechanical transmission structure to drive the lifting screw to move up and down. For example, the output shaft of the lifting motor is fitted with a gear one, the transmission device is rotatably mounted on the top of the molten salt tank through bearings, and a gear two is fitted outside the transmission device. Gear one and gear two are driven by meshing or belt transmission. The transmission device is hollow inside for the lifting screw to pass through, and a toothed ring is fixed on the inner wall to mesh with the thread of the lifting screw. As the toothed ring rotates, it drives the lifting screw to move axially. The lifting connecting rod is used to connect at the lower part of the mounting frame, driving the spiral coil assembly connected to the mounting frame to move up and down with the lifting screw. During operation, the operation of the lifting mechanism is precisely controlled by collecting the heat transfer oil outlet temperature. The outer periphery of the lifting screw is also equipped with a heat-insulating ceramic tube. The inside of the heat-insulating ceramic tube is hollow, with the upper end connected to the top of the molten salt tank and the lower end connected to the lifting connecting rod, which can avoid the influence of high temperature on the lifting screw.

[0015] This utility model has the following advantages:

[0016] 1. By implementing this utility model, direct and controllable heat exchange can be achieved in molten salt storage tanks. The heat exchange efficiency is high and the system thermal energy utilization rate is higher than that of traditional molten salt heat exchange systems. The implementation of this equipment system can reduce system investment, has obvious advantages in system operation benefits, and is easy to control digitally.

[0017] 2. This utility model uses a multi-layer variable diameter spiral heat exchange coil and its lifting mechanism, which can precisely adjust the heat exchange area according to the heat exchange efficiency and the molten salt temperature range, as the heat exchange equipment between the heat transfer oil and the molten salt. It directly achieves efficient heat exchange in the molten salt tank and has the characteristics of high heat exchange efficiency, low equipment investment, and low operation and maintenance costs. The equipment has small thermal lag and can meet the requirements of precise digital and intelligent control, which can effectively improve the thermal efficiency of the overall heating system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] Figure 2 This is a schematic diagram of the spiral coil structure.

[0020] In the diagram: 1. Molten salt tank; 2. Spiral coil; 3. Oil inlet manifold; 4. Oil outlet manifold; 5. Oil inlet; 6. Oil outlet; A. Inlet end; 8. Downcomer pipe; 9. Spiral riser pipe; 10. Oil outlet pipe; 11. Fin; 12. Lifting motor; 13. Transmission device; 14. Lifting screw; 15. Lifting connecting rod; 16. Insulated ceramic tube. Detailed Implementation

[0021] 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. The components of the embodiments of this utility model described and shown in the accompanying drawings can typically be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] Example 1: As Figure 1 and 2 As shown, a multi-layer variable diameter spiral molten salt heat exchanger includes a lifting mechanism and a spiral coil 2 assembly. The lifting mechanism drives the spiral coil 2 assembly to move up and down in the molten salt tank 1. The spiral coil 2 assembly includes a spiral coil 2, an oil inlet manifold 3, and an oil outlet manifold 4. An oil inlet 5 is provided on the oil inlet manifold 3. An oil outlet 6 is provided on the oil outlet manifold 4. The spiral coil 2 is spirally coiled below the oil inlet manifold 3 and the oil outlet manifold 4.

[0028] The spiral coil 2, along the direction of heat transfer oil flow, includes, in sequence, an inlet end A, a downcomer pipe 8, a spiral ascender pipe 9, and an oil outlet pipe 10; the inlet end A is located at the top of the spiral coil 2 and is connected to the oil inlet manifold 3; the downcomer pipe 8 extends downward from the inlet end A to the bottom of the spiral coil 2; the spiral ascender pipe 9 spirals upward from the end of the downcomer pipe 8 to the top of the spiral coil 2; the end of the spiral ascender pipe 9 is connected to the oil outlet pipe 10; the oil outlet pipe 10 is connected to the oil outlet manifold.

[0029] The surface of the spiral coil 2 is welded with fins 11; the fins 11 connect the upper and lower adjacent spiral riser pipes 9;

[0030] The vertical spacing between the two adjacent spiral riser pipes 9 is 10-15cm;

[0031] The spiral coil 2 assembly includes at least two spiral coils 2; when the number of spiral coils 2 is ≥2, the central axes of each spiral coil 2 coincide, and the spiral outer diameter of each spiral coil 2 increases sequentially from the central axis outward.

[0032] The minimum outer diameter of the spiral coil 2 located in the innermost circle is 40cm;

[0033] The lifting mechanism includes a lifting motor 12, a transmission device 13, a lifting screw 14, a lifting connecting rod 15, and a mounting frame 16. The lifting motor 12 drives the lifting screw 14 to move up and down through the transmission device 13. The lifting screw 14 extends into the molten salt tank 1 and is connected to the mounting frame through the lifting connecting rod 15. The mounting frame is fixedly connected to the oil inlet manifold 3 and the oil outlet manifold 4. In this utility model, the lifting motor 12 and the transmission device 13 can adopt a conventional mechanical transmission structure to drive the lifting screw 14 to move up and down. For example, the output shaft of the lifting motor 12 is fitted with a gear 1, the transmission device 13 is rotatably mounted on the top of the molten salt tank 1 through bearings, and the transmission device 13 is fitted with a gear 2 on the outside. The gear 1 and gear 2 are driven by meshing or belt transmission. The transmission device 13 is hollow inside for the lifting screw 14 to pass through, and a toothed ring is fixed on the inner wall to mesh with the lifting screw 14. As the toothed ring rotates, it drives the lifting screw to move axially. The lifting connecting rod 15 serves as a connection at the lower part of the mounting frame, driving the spiral coil 2 assembly connected to the mounting frame to move up and down with the lifting screw 14. During operation, the operation of the lifting mechanism is precisely controlled by collecting the heat transfer oil outlet temperature. A heat-insulating ceramic tube 16 is also provided around the outer periphery of the lifting screw 14. The heat-insulating ceramic tube 16 is hollow inside, with its upper end connected to the top of the molten salt tank 1 and its lower end connected to the lifting connecting rod 15 to prevent high temperatures from affecting the lifting screw 14.

[0034] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-layer variable diameter spiral molten salt heat exchanger, characterized in that: It includes a lifting mechanism and a spiral coil assembly; the lifting mechanism drives the spiral coil assembly to move up and down in the molten salt tank; the spiral coil assembly includes a spiral coil, an oil inlet manifold, and an oil outlet manifold; the oil inlet manifold is provided with an oil inlet; the oil outlet manifold is provided with an oil outlet; the spiral coil is spirally coiled below the oil inlet manifold and the oil outlet manifold.

2. The multi-layer variable diameter spiral molten salt heat exchanger according to claim 1, characterized in that: The spiral coil includes, in sequence along the direction of heat transfer oil flow, an inlet end, a downcomer pipe, a spiral riser pipe, and an oil outlet pipe; the inlet end is located at the top of the spiral coil and is connected to the oil inlet manifold; the downcomer pipe extends downward from the inlet end to the bottom of the spiral coil; the spiral riser pipe spirals upward from the end of the downcomer pipe to the top of the spiral coil; the end of the spiral riser pipe is connected to the oil outlet pipe; and the oil outlet pipe is connected to the oil outlet manifold.

3. The multi-layer variable diameter spiral molten salt heat exchanger according to claim 2, characterized in that: Fins are welded to the surface of the spiral coil; the fins connect two adjacent spiral rising pipes.

4. The multi-layer variable diameter spiral molten salt heat exchanger according to claim 2, characterized in that: The vertical spacing between adjacent spiral riser pipes in the upper and lower layers is 10-15cm.

5. The multi-layer variable diameter spiral molten salt heat exchanger according to claim 1, characterized in that: The spiral coil assembly includes at least two spiral coils; when the number of spiral coils is greater than or equal to two, the central axes of each spiral coil coincide, and the outer diameter of each spiral coil increases sequentially from the central axis outward.

6. The multi-layer variable diameter spiral molten salt heat exchanger according to claim 4, characterized in that: The minimum outer diameter of the spiral coil located in the innermost ring is 40 cm.

7. The multi-layer variable diameter spiral molten salt heat exchanger according to claim 1, characterized in that: The lifting mechanism includes a lifting motor, a transmission device, a lifting screw, a lifting connecting rod, and a mounting frame; the lifting motor drives the lifting screw to move up and down through the transmission device; the lifting screw extends into the molten salt tank and is connected to the mounting frame through the lifting connecting rod; the mounting frame is fixedly connected to the oil inlet manifold and the oil outlet manifold.

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