An even-heated molten salt electric heating tube and electric heater for flow dead zone

Abstract

The application discloses a kind of even-heated molten salt electric heating tubes for flow dead zone, electric heater belongs to molten salt electric heating tube technical field, even-heated molten salt electric heating tube includes metal outer tube, heating wire, insulating heat-conducting filler and even-heated element;Heating wire is set to the inside of metal outer tube, and insulating heat-conducting filler is filled in the inside of metal outer tube;Even-heated element uses high thermal conductivity material, even-heated element is attached to the inner wall surface of metal outer tube, the position of even-heated element corresponds with the existence of flow slow area in the outside environment of even-heated molten salt electric heating tube, and even-heated element can form axial heat conduction channel in the inside of metal outer tube;Even-heated element can conduct heat of flow slow area to flow fast area, realize temperature dynamic balance.The application can effectively eliminate the overtemperature risk of flow dead zone, transfer the heat accumulated in flow dead zone to flow active area, realize temperature dynamic balance, cost control is better, and structure design is convenient.

Description

Technical Field

[0001] This invention belongs to the field of molten salt electric heating tube technology, specifically relating to a homogenizing molten salt electric heating tube and electric heater for flow dead zones. Background Technology

[0002] Currently, in shell-and-tube molten salt electric heaters, baffles are typically installed on the shell side to enhance heat transfer. However, baffles inevitably create "flow dead zones" on the surface of the heating tube, where the molten salt flow velocity is extremely low or even stagnant in certain areas (such as the backflow side near the baffle cut). In these dead zones, the heat transfer efficiency of the heating tube surface drops sharply, but the heat generated by the heating wire continues to be transferred, causing the tube wall and adjacent molten salt temperatures in this area to be much higher than in other areas. This can easily lead to localized overheating and decomposition of the molten salt, potentially causing the heating tube to burn out.

[0003] As an improvement, current technologies mainly address this problem by optimizing the design of baffles or increasing the overall flow rate. However, improving the local overheating decomposition of molten salt by optimizing the design of baffles or increasing the overall flow rate has relatively limited effect and may significantly increase the manufacturing cost of the structure. It cannot effectively achieve dynamic temperature equilibrium, and a direct and efficient solution for the flow dead zone itself needs further optimization. Summary of the Invention

[0004] This invention provides a homogenizing molten salt electric heating tube for flow dead zones. The purpose is to solve the problem that in current shell-and-tube molten salt electric heaters, improving the local overheating decomposition of molten salt by optimizing the design of baffles or increasing the overall flow rate has relatively limited effect and may significantly increase the manufacturing cost of the structure. It cannot effectively achieve dynamic temperature balance, and there is still a need for further optimization of a direct and efficient solution for the flow dead zones themselves.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a homogenizing molten salt electric heating tube for flow dead zones, comprising a heating tube body, which includes a metal outer tube, a heating wire, an insulating thermally conductive filler, and at least one homogenizing element; wherein: The heating wire is placed inside the metal outer tube, and the insulating and thermally conductive filler fills the inside of the metal outer tube and covers the heating wire; The heat spreader is made of a high thermal conductivity material and is attached to the inner wall of the outer metal tube. The position of the heat spreader corresponds to the slow-flowing region in the external environment of the heat spreader molten salt electric heating tube. The heat spreader can form an axial heat conduction channel inside the outer metal tube. When the molten salt flows inside the outer metal tube, the heat spreader can conduct at least a portion of the heat from the slow-flowing region to the fast-flowing regions on both sides to achieve dynamic temperature balance.

[0006] In some implementations, the heat spreader element adopts a helical spring-like structure, and the pitch of the helical spring-like structure can be adjusted.

[0007] Furthermore, the pitch of the helical spring-like structure can be adjusted according to the heat load and heat distribution requirements of the homogenizing molten salt electric heating tube.

[0008] In some implementations, the heat spreader adopts a segmented structure, with gaps reserved between the segments or connected by thermally conductive connectors.

[0009] Furthermore, the thermally conductive connector includes copper wire.

[0010] In some implementations, the heat spreader element can be fixed to the inner wall of the outer metal tube by means of tube expansion or by clamps.

[0011] In some implementations, the high thermal conductivity material includes copper, aluminum alloy, or high thermal conductivity metal composite material.

[0012] In some implementations, magnesium oxide powder is used as the insulating and thermally conductive filler.

[0013] In some implementations, the outer metal tube is made of stainless steel.

[0014] The present invention also provides an electric heater comprising at least a portion of the above-described homogenizing molten salt electric heating tube for flow dead zones.

[0015] Compared with the prior art, the molten salt electric heating tube of the present invention, which is designed for homogenization of flow dead zones, has the following beneficial effects: This invention discloses a homogenizing molten salt electric heating tube for addressing flow dead zones. A homogenizing element made of a highly thermally conductive material is tightly mounted on the inner wall of the outer metal tube of the heating tube. This homogenizing element is preferably in the shape of a helical spring, as it provides a large contact area and is easy to install. The installation position of the homogenizing element must be precisely positioned according to the arrangement of the baffles inside the electric heater to ensure that it covers the expected flow dead zone caused by the baffles.

[0016] This invention addresses the root cause of flow dead zones through precise and efficient design. It involves adding a standard component (spring) to the existing heating tube without altering the external system, resulting in low cost and ease of implementation and promotion. The spring structure provides an axial heat flow channel, and its spiral shape enhances circumferential heat distribution, achieving a dual heat distribution effect. This fundamentally avoids localized coking and overheating accidents caused by flow dead zones, significantly extending the service life of the heating tube and the entire system. The heat-dissipating molten salt electric heating tube of this invention directly and efficiently eliminates the risk of overheating in flow dead zones. Its purpose is not to eliminate the flow dead zone itself, but rather to rationally transfer the heat accumulated in the flow dead zone to the actively flowing area through a built-in, highly thermally conductive, and structurally designed heat-dissipating element, thereby achieving dynamic temperature equilibrium. Furthermore, the invention features a convenient structural design, excellent cost control, and certain engineering applicability. Attached Figure Description

[0017] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a schematic diagram of the structure of a homogenizing molten salt electric heating tube for flow dead zones according to the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of a homogenizing molten salt electric heating tube for the flow dead zone according to the present invention.

[0019] Among them, 1. metal outer tube, 2. heating wire, 3. insulating and thermally conductive filler, 4. heat spreader element, 5. baffle plate, 6. flow dead zone, 7. electric heater shell. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the 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 invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0023] It should be noted that the apparatus and methods disclosed in the embodiments herein can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings show the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments herein. In this regard, each block in a flowchart or block diagram may represent a module, program, or part of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system to perform the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0024] Furthermore, the functional modules in the various embodiments described herein can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part. Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention. After reading the above content, various modifications and substitutions of the present invention will be obvious to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

[0025] How to provide a homogenizing molten salt electric heating tube that can directly and efficiently eliminate the risk of overheating in the flow dead zone, by using a built-in high thermal conductivity homogenizing element to transfer the heat accumulated in the dead zone to the area with a faster flow rate, thereby achieving dynamic temperature balance of the electric heating tube.

[0026] like Figure 1 and Figure 2 As shown, the present invention provides a homogenizing molten salt electric heating tube for flow dead zones, comprising a heating tube body, which includes a metal outer tube 1, a heating wire 2, an insulating thermally conductive filler 3, and at least one homogenizing element 4; wherein: The heating wire 2 is disposed inside the metal outer tube 1, and the insulating and thermally conductive filler 3 fills the inside of the metal outer tube 1 and covers the heating wire 2; The heat spreader 4 is made of a high thermal conductivity material and is attached to the inner wall of the outer metal tube 1. The position of the heat spreader 4 corresponds to the slow-flowing region in the external environment of the heat spreader molten salt electric heating tube. The heat spreader 4 can form an axial heat conduction channel inside the outer metal tube 1. When the molten salt flows inside the outer metal tube 1, the heat spreader 4 can conduct at least a portion of the heat from the slow-flowing region to the fast-flowing regions on both sides to achieve dynamic temperature balance.

[0027] To address the issue that the baffles 5 in current shell-and-tube molten salt electric heaters inevitably form a flow dead zone 6, where the molten salt flow velocity is low and heat exchange efficiency is poor, leading to heat accumulation and localized overheating, which in turn causes molten salt decomposition and heating tube burnout, this invention addresses the problem of heat accumulation in the flow dead zone 6 by attaching a high thermal conductivity heat-spreading element 4 to the inner wall of the outer metal tube 1, corresponding to the location of the flow dead zone 6 (slow-flow region). This creates an axial heat conduction channel, directly providing a solution to the heat accumulation problem without modifying the external system, making it more targeted and economical. The heat-spreading element 4, with its high thermal conductivity, can quickly transfer heat from the flow dead zone 6 to the low-temperature, fast-flowing regions on both sides, thereby achieving dynamic temperature balance and fundamentally preventing localized overheating, effectively solving the problems of molten salt decomposition and heating tube burnout. Furthermore, this invention only adds the heat-spreading element 4 to the existing heating tube structure, making the structure convenient and easy to modify, requiring no additional investment in complex equipment or processes, reducing production and application costs, and improving the operational safety and service life of the molten salt electric heating tube.

[0028] Specifically, in the homogenized molten salt electric heating tube for the flow dead zone of this invention, the homogenizing element 4 adopts a helical spring structure with adjustable pitch. This helical spring structure maximizes the contact area between the homogenizing element 4 and the inner wall of the metal outer tube 1 and the insulating thermally conductive filler 3, resulting in a shorter heat transfer path and more thorough contact, significantly improving heat conduction efficiency and ensuring that the heat in the flow dead zone 6 can be quickly absorbed and conducted by the homogenizing element 4. The adjustable pitch design provides adaptability; it eliminates the need to replace the overall structure of the homogenizing element 4, allowing for adaptation to different sizes of heating tubes or different installation scenarios simply by adjusting the pitch. This avoids redesign and remanufacturing due to changes in scenarios, reducing adaptation costs. Furthermore, the helical spring structure itself possesses a certain degree of elasticity, allowing for better contact with the inner wall of the metal outer tube 1 during installation, reducing contact gaps and further ensuring the stability of heat conduction.

[0029] Furthermore, in the homogenizing molten salt electric heating tube for the flow dead zone, the pitch of the spiral spring-like structure can be adjusted according to the heat load and homogenization requirements of the heating tube, making the structural design of the homogenizing element 4 more precise. Under different operating conditions, the heat load of the heating tube varies, and the requirements for homogenization also differ. When the heat load is high, the heat conduction area and density of the homogenizing element 4 can be increased by reducing the pitch, thereby improving heat transfer capacity. When the heat load is low, the pitch can be increased to reduce material usage, saving costs while ensuring homogenization. This on-demand adjustment design avoids the problems of insufficient homogenization or material waste caused by a fixed pitch, ensuring that the homogenizing element 4 achieves optimal homogenization under different operating conditions. This guarantees the stability of the heating tube operation and achieves a balance between material usage and homogenization effect.

[0030] As a preferred embodiment, in the homogenizing molten salt electric heating tube for flow dead zones, the present invention employs a segmented structure for the homogenizing element 4, with gaps reserved between each segment or connected by thermally conductive connectors. This fully considers the distribution characteristics of flow dead zones, which in practical applications are typically distributed intermittently rather than continuously on the heating tube. The segmented structure allows the homogenizing element 4 to be placed only in the areas where flow dead zones 6 exist, without needing to cover the entire length of the heating tube, significantly reducing the amount of high thermal conductivity material used. The gaps reserved between each segment further optimize costs, while the connection via thermally conductive connectors ensures the continuity of heat conduction between the segments of the homogenizing element 4, making it suitable for scenarios where flow dead zones 6 are distributed close together or where high requirements for continuous heat conduction are needed.

[0031] In this invention, the heat-conducting connector in the homogenizing molten salt electric heating tube for the flow dead zone is made of copper wire. The thermal conductivity of copper wire can ensure the heat transfer efficiency between the segmented homogenizing elements, avoid the interruption of heat transfer due to poor thermal conductivity of the connector, ensure the integrity of the axial heat conduction channel, and thus maintain the temperature balance of the entire heating tube.

[0032] This invention addresses the issue of heat-spreading molten salt electric heating tubes designed for flow dead zones. In this tube, the heat-spreading element 4 is fixed to the inner wall of the outer metal tube 1 via tube expansion or clamping. This adapts to various scenarios. Tube expansion ensures a tight fit between the heat-spreading element 4 and the inner wall of the outer metal tube 1, completely eliminating gaps and maximizing heat transfer efficiency. Furthermore, the fixed structure is stable and less prone to displacement during operation, ensuring the heat-spreading element 4 remains aligned with the flow dead zone 6 and guaranteeing stable heat spread. Clamping, on the other hand, offers convenient installation and disassembly. Subsequent maintenance or replacement of the heat-spreading element 4 eliminates the need for destructive operations on the outer metal tube 1, reducing maintenance costs and difficulty. This method is suitable for scenarios requiring frequent maintenance or component replacement.

[0033] Furthermore, in the homogenizing molten salt electric heating tube for the flow dead zone, the high thermal conductivity material includes copper, aluminum alloy, or high thermal conductivity metal composite material. By using materials with excellent thermal conductivity, the core requirement of rapid heat transfer for the homogenizing element 4 can be met. Copper has a high thermal conductivity, achieving optimal heat transfer efficiency, and is suitable for scenarios with stringent requirements for homogenization. Aluminum alloy has the advantages of relatively low cost and light weight, reducing the overall cost and weight of the product while ensuring certain thermal conductivity. High thermal conductivity metal composite material can balance multiple properties such as thermal conductivity, mechanical strength, and corrosion resistance according to requirements, adapting to more complex working environments.

[0034] In this invention, a homogenized molten salt electric heating tube for the flow dead zone utilizes magnesium oxide powder as the insulating and thermally conductive filler 3. Magnesium oxide powder is a traditional filler with both excellent insulation and thermal conductivity. Its insulation properties effectively isolate the heating wire from the metal outer tube 1 and the homogenizing element 4, preventing short-circuit accidents and ensuring the electrical safety of the heating tube. Simultaneously, the high thermal conductivity of magnesium oxide powder allows for rapid transfer of heat generated by the heating wire to the homogenizing element and the metal outer tube. This ensures that the homogenizing element 4 can promptly absorb and conduct heat from the flow dead zone 6, guaranteeing the effective operation of the heat diversion mechanism, and also assists the metal outer tube in transferring heat to the molten salt, improving overall heat exchange efficiency.

[0035] As an alternative approach, in the homogenizing molten salt electric heating tube for the flow dead zone, the metal outer tube 1 can be made of stainless steel. Stainless steel possesses excellent high-temperature resistance and corrosion resistance, enabling it to adapt to the high-temperature environment and chemical properties of molten salt during the heating process. This prevents damage to the metal outer tube due to high-temperature oxidation or molten salt corrosion, significantly extending the service life of the heating tube. Simultaneously, stainless steel possesses high mechanical strength and structural stability, providing a reliable mounting foundation for the homogenizing element. This ensures that the homogenizing element 4 will not be affected by deformation of the outer tube during installation and operation, guaranteeing the stability of heat conduction.

[0036] The present invention also provides an electric heater, which includes an electric heater housing 7, a baffle plate 5, and a heating tube bundle. At least some of the heating tubes are homogenized molten salt electric heating tubes designed to target flow dead zones, and the arrangement of the homogenizing element 4 matches the region of the flow dead zone 6 formed by the baffle plate 5 on the tube wall. Based on this, dynamic temperature balance of the electric heater can be achieved, thereby improving the service life of the electric heater.

[0037] In some embodiments, in a homogenizing molten salt electric heating tube for flow dead zones according to the present invention, a homogenizing element 4 made of a high thermal conductivity material is tightly mounted on the inner wall of the outer metal tube 1 of the heating tube. This homogenizing element 4 is preferably helical spring-shaped because it provides a large contact area and is easy to install. Crucially, the installation position of the homogenizing element 4 needs to be precisely positioned according to the arrangement of the baffles 5 inside the electric heater to ensure that it covers the expected flow dead zone 6 caused by the baffles 5.

[0038] This invention discloses a homogenizing molten salt electric heating tube for flow dead zones. The heat diversion mechanism is as follows: In the flow dead zone 5, due to poor heat dissipation, heat begins to accumulate, causing the temperature of the tube wall and the corresponding section of the built-in homogenizing element to rise, resulting in heat buildup. The highly thermally conductive, spring-shaped homogenizing element 4 acts as an efficient axial heat conduction channel. The heat from its temperature-rising portion is rapidly conducted along the spring to the lower-temperature areas on both sides (i.e., areas with active molten salt flow and good heat exchange), forming axial heat conduction. The heat conducted to the fast-flowing areas is quickly carried away by the high-speed flowing molten salt, achieving heat release. This process creates a continuous heat diversion effect, preventing excessive heat accumulation in the flow dead zone 6, thus maintaining its temperature at a level close to that of the active zone, avoiding local overheating, and achieving dynamic temperature balance.

[0039] In some embodiments, during assembly, the homogenizing molten salt electric heating tube of the present invention first inserts a highly thermally conductive spiral spring-shaped structure into the interior of a stainless steel outer tube, fixing it tightly against the inner wall in a predetermined position (this can be achieved through slight tube expansion or temporary clamps). Then, the heating wire 2 is placed in the center of the stainless steel outer tube, followed by the filling, compaction, and encapsulation of magnesium oxide powder. During the overall assembly of the electric heater, it is ensured that the section of the highly thermally conductive spiral spring-shaped structure is accurately aligned with the flow dead zone 6 generated by the baffle plate 5. When the electric heater is in operation, a homogenizing heat dissipation effect is achieved.

[0040] In summary, this invention provides a homogenized molten salt electric heating tube and heater specifically designed for flow dead zones, effectively mitigating the localized overheating problem of the electric heating tube within the molten salt flow dead zone caused by the baffle plate 5. During operation, the heat from the heating wire 2 is transferred through magnesium oxide to the entire helical spring-like structure. The spring in this structure, with its excellent thermal conductivity, rapidly conducts heat axially from the slow-flowing region to the fast-flowing regions on both sides, achieving efficient heat diversion and significantly balancing the tube wall temperature, fundamentally eliminating the risk of overheating in the dead zone. From a cost and manufacturing perspective, since this structure is only introduced in the flow dead zone, cost control is better, and the overall reliability of the homogenized molten salt electric heating tube is improved.

[0041] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Anyone skilled in the art can readily implement the present invention according to the description and above. Any modifications, alterations, or variations made based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A homogenizing molten salt electric heating tube for flow dead zones, characterized in that, The heating tube body includes a metal outer tube (1), a heating wire (2), an insulating thermally conductive filler (3), and at least one heat spreader element (4); wherein: The heating wire (2) is disposed inside the metal outer tube (1), and the insulating thermally conductive filler (3) is filled inside the metal outer tube (1) and covers the heating wire (2). The heat-spreading element (4) is made of a high thermal conductivity material. The heat-spreading element (4) is attached to the inner wall of the metal outer tube (1). The position of the heat-spreading element (4) corresponds to the slow-flowing region in the external environment of the heat-spreading molten salt electric heating tube. The heat-spreading element (4) can form an axial heat conduction channel inside the metal outer tube (1). When the molten salt flows inside the metal outer tube (1), the heat-spreading element (4) can conduct at least a portion of the heat from the slow-flowing region to the fast-flowing regions on both sides in order to achieve dynamic temperature balance.

2. The homogenizing molten salt electric heating tube for flow dead zones according to claim 1, characterized in that, The heat-spreading element (4) adopts a spiral spring-like structure, and the pitch of the spiral spring-like structure can be adjusted.

3. The homogenizing molten salt electric heating tube for flow dead zones according to claim 2, characterized in that, The pitch of the spiral spring-like structure can be adjusted according to the heat load and heat equalization requirements of the homogenizing molten salt electric heating tube.

4. The homogenizing molten salt electric heating tube for flow dead zones according to claim 1, characterized in that, The heat-spreading element (4) adopts a segmented structure, and the segments of the heat-spreading element (4) are reserved with gaps or connected by heat-conducting connectors.

5. The homogenizing molten salt electric heating tube for flow dead zones according to claim 4, characterized in that, The thermally conductive connector includes copper wire.

6. The homogenizing molten salt electric heating tube for flow dead zones according to claim 1, characterized in that, The heat-spreading element (4) can be fixed to the inner wall of the metal outer tube (1) by means of tube expansion or by clamp.

7. The homogenizing molten salt electric heating tube for flow dead zones according to claim 1, characterized in that, The high thermal conductivity material includes copper, aluminum alloy, or high thermal conductivity metal composite material.

8. The homogenizing molten salt electric heating tube for flow dead zones according to claim 1, characterized in that, The insulating and thermally conductive filler (3) is made of magnesium oxide powder.

9. The homogenizing molten salt electric heating tube for flow dead zones according to claim 1, characterized in that, The metal outer tube (1) is made of stainless steel.

10. An electric heater, characterized in that, Includes at least a portion of the homogenized molten salt electric heating tube for flow dead zones as described in any one of claims 1-9.

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