A high-efficiency molten salt heat exchanger with built-in distributed heat tracing disturbance

Abstract

The application relates to the technical field of molten salt heat exchangers, in particular to a high-efficiency molten salt heat exchanger with built-in distributed heat tracing disturbance, which comprises a shell, a hot liquid inlet and a hot liquid outlet are fixedly connected to the two ends of the shell, fixed plates one are fixedly installed on the two sides in the shell, molten salt pipes are installed between the fixed plates one and are provided with multiple heat exchange pipes, the heat exchange pipes are located in the molten salt pipes and are coaxially arranged with the molten salt pipes, and multiple heat conduction fins are fixedly connected to the outer walls of the heat exchange pipes along the length direction of the heat exchange pipes. The application forms a head-on rotational flow through the heat conduction fins and the elastic disturbance fins in a forward and reverse staggered spiral mode, breaks the flow stagnation layer of the pipe wall surface, improves the uneven heat exchange problem, and switches three flow states through the self-adaptive deformation of the elastic disturbance fins according to the flow, adapts to the heat exchange under the flow fluctuation state, simultaneously relies on the flow fluctuation to drive the heat exchange pipes to reciprocatingly move through the tension spring, cooperatively self-cleanses through multiple actions, suppresses heat exchange attenuation, and avoids pipe blockage hidden dangers.

Description

Technical Field

[0001] This invention relates to the field of molten salt heat exchanger technology, and more particularly to a high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence. Background Technology

[0002] Molten salt heat exchangers are shell-and-tube special heat exchange equipment adapted to high-temperature heat transfer conditions. They use high-temperature molten inorganic salt as the heat exchange medium on one side, separating the molten salt from water, steam, or other heat exchange fluids through the tube wall to complete heat transfer. This enables the molten salt to absorb and store heat or release heat to generate steam, and is widely used in high-temperature thermal energy utilization scenarios such as solar thermal power generation and energy storage peak shaving.

[0003] In the conventional operation scenario of molten salt exothermic steam generation in solar thermal power plants, the unit needs to cooperate with the grid to frequently increase and decrease the load. The molten salt transport flow rate will be in a state of large fluctuation for a long time. However, the internal medium flow direction of the traditional molten salt heat exchanger is always fixed and the internal turbulence components are all fixed structures that cannot be deformed, and cannot adjust the flow field shape in real time with the flow rate change. Furthermore, during the steady flow of molten salt, a thick flow stagnation layer continuously forms at the contact surfaces of the outer and inner walls of the heat exchange tubes. The flow velocity in the stagnation areas is extremely low, thus forming flow dead zones. This not only increases the thermal resistance of the tube wall and weakens the heat transfer efficiency, but also leads to significant hot-cold differentiation. That is, the molten salt close to the outer wall of the heat exchange tube accumulates heat and undergoes local overheating and decomposition, while the molten salt near the inner wall of the molten salt tube has less contact heat and insufficient heating, resulting in poor heat exchange uniformity. Under low flow and low load conditions, the stagnation layer retention effect is further aggravated, and the excessive residence time of molten salt accelerates the deterioration of the medium. Under high flow and full load conditions, the overall flow velocity of the molten salt is too fast, the effective heat exchange time is insufficient, and the heat absorption is incomplete. Ultimately, this results in a low overall heat exchange utilization rate of the heat exchanger and insufficient heat transfer stability under variable load conditions, making it difficult to adapt to the actual operating requirements of frequent peak shaving in solar thermal power plants.

[0004] To address the aforementioned technical shortcomings, a solution is proposed that aims to provide adaptive enhanced heat exchange and multiple synergistic self-cleaning mechanisms, adapting to different flow rate conditions and improving heat exchange efficiency and long-term operational stability. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence to solve the aforementioned technical defects.

[0006] The objective of this invention can be achieved through the following technical solution: a high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence, comprising a shell, wherein a hot liquid inlet and a hot liquid outlet are fixedly connected to both ends of the shell respectively, and a fixing plate is fixedly installed on both sides inside the shell; Molten salt pipes are installed between fixed plates and multiple of them are provided. An insulation layer is installed between the fixed plates and outside the molten salt pipes. The heat exchange tube is located inside the corresponding molten salt tube and is coaxially arranged with it. Multiple heat-conducting fins are fixedly connected to the outer wall of the heat exchange tube along its length. The heat exchange tube uses the heat-conducting fins to further increase the heat exchange area and guide the low-temperature molten salt to swirl around the heat exchange tube, thus extending the heat exchange path. Multiple elastic baffles are arranged along the length of the heat exchange tube. The heat-conducting plate is located between two adjacent sets of elastic baffles, which guides the low-temperature molten salt between the two adjacent sets of heat-conducting plates to swirl in the opposite direction. This allows the low-temperature molten salt to be mixed in a turbulent manner, improving the heat exchange uniformity, while also impacting and self-cleaning the scale inside the molten salt tube. When the elastic baffle is impacted by the flow of low-temperature molten salt, it undergoes compression deformation along the length of the heat exchange tube and operates in three different compression states under different pressure forces: medium-pressure flow, low-pressure smooth flow, and high-pressure slow flow.

[0007] Preferably, a second fixing plate is fixedly installed inside the shell on the opposite side of the two sets of fixing plates. A liquid injection chamber is formed between the first fixing plate and the second fixing plate on the hydrothermal inlet side, and a liquid outlet chamber is formed between the first fixing plate and the second fixing plate on the hydrothermal outlet side. Both the liquid injection chamber and the liquid outlet chamber are connected to the molten salt pipe.

[0008] Preferably, a molten salt inlet pipe communicating with the injection chamber is fixedly installed at the bottom of the shell, and a molten salt outlet pipe communicating with the outlet chamber is fixedly installed at the top of the shell.

[0009] Preferably, the heat exchange tube is slidably connected to two sets of fixed plates, a hot liquid inlet cavity is formed between the hot liquid inlet and the fixed plate, a hot liquid outlet cavity is formed between the hot liquid outlet and the corresponding fixed plate, and the heat exchange tube communicates with the hot liquid inlet cavity and the hot liquid outlet cavity.

[0010] Preferably, both the heat-conducting plate and the elastic baffle are 180° twisted helical blades, the heat-conducting plate and the elastic baffle rotate in opposite directions, and two sets of the heat-conducting plate and the elastic baffle are arranged in an array along the annular outer wall of the heat exchange tube, and the heat-conducting plate and the elastic baffle are staggered along the circumference of the heat exchange tube.

[0011] Preferably, the heat-conducting plate is slidably connected to the inner wall of the molten salt tube, the elastic baffle is slidably connected to the molten salt tube and the heat exchange tube, and a plurality of mounting rings rotatably mounted on the outer wall of the heat exchange tube and rotatably connected to the corresponding elastic baffle.

[0012] Preferably, a limiting pin is fixedly installed on the molten salt tube at the corresponding mounting ring position, and the limiting pin abuts against the arc-shaped convex side of the corresponding elastic baffle.

[0013] Preferably, the thickness of the elastic baffle plate continuously increases along the flow direction of the low-temperature molten salt, and the thick end of the elastic baffle plate has a circular arc cone structure.

[0014] Preferably, the compression length of the elastic baffle during medium-pressure flow is greater than the compression length during low-pressure free flow, but less than the compression length during high-pressure slow flow.

[0015] Preferably, a circular plate is fixedly connected to one end of the heat exchange tube at the outlet of the hot liquid, and a tension spring is fixedly connected between the circular plate and the corresponding fixed plate, and a telescopic protective tube is fixedly connected to the outside of the tension spring.

[0016] The beneficial effects of this invention are as follows: (1) The present invention adopts a combination structure of spiral twisted heat-conducting plates and elastic turbulence plates with opposite rotation and circumferential staggered arrangement: when the low temperature molten salt flows through, it forms a forward swirling flow and a reverse swirling flow in turn. The two swirling flows collide and mix with each other, continuously destroying the fluid boundary layer of the tube wall, eliminating the dead zone of flow stagnation in the tube, effectively improving the uneven heat exchange defects of local overheating of molten salt on the inner wall of the heat exchange tube and insufficient heating of molten salt on the inner wall of the outer molten salt tube in the traditional shell-and-tube molten salt heat exchanger. In addition, the effective heat exchange area is further increased by the heat-conducting plates, while the actual flow path of molten salt is extended, thus improving the heat exchange effect. Furthermore, the elastic baffles have a gradually varying thickness along the flow direction and automatically generate different compression deformations with the help of the molten salt flow impact force, achieving self-adjustment of three working states: low-pressure smooth flow, medium-pressure diversion, and high-pressure slow flow. Under rated flow velocity, moderate compression extends the residence time of molten salt heat exchange, ensuring stable heat exchange efficiency. Under low flow velocity conditions, the elastic baffles rebound and the pitch increases to reduce flow resistance, preventing molten salt from remaining at high temperature and decomposing for a long time. Under high flow and high pressure conditions, further compression reduces the pitch and slows down the flow velocity, ensuring that the molten salt absorbs heat fully and completely under high load conditions. It can automatically adapt to scenarios with frequent fluctuations in the flow of the molten salt system, making the heat exchange uniformity, heat transfer stability, and overall heat exchange efficiency superior to traditional tube bundle molten salt heat exchange structures.

[0017] (2) The present invention also drives the heat exchange tube to reciprocate through the axial thrust generated by the fluctuation of molten salt flow and the spring return force, the heat conduction plate slides with the inner wall of the molten salt tube, continuously scraping away the molten salt scale gradually deposited on the tube wall, avoiding the accumulation and thickening of scale layer to block heat transfer, and the elastic turbulence plate generates bending stress repeatedly during the long-term compression and rebound cycle deformation process, causing the scale attached to its own surface to stress crack and peel off on its own, thus achieving self-cleaning; Furthermore, during the reciprocating movement of the heat exchange tube, the limiting pin and the rotating action of the mounting ring cause the elastic turbulence plate to deflect slightly in both directions, continuously changing the circumferential misalignment angle between the plate and the heat-conducting plate. Combined with the Venturi acceleration effect formed by the small gap between the mounting ring and the inner wall of the molten salt tube, the molten salt jet washes away the fine deposits on the outer wall of the heat exchange tube and the surface of the heat-conducting plate, thereby significantly slowing down the heat exchange decay rate of the heat exchanger and avoiding the risk of increased flow resistance and freezing blockage caused by scaling and clogging. Attached Figure Description

[0018] The invention will now be further described with reference to the accompanying drawings; Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the housing of the present invention; Figure 3 This is a schematic diagram of the assembly of the molten salt tube and the heat exchange tube of the present invention; Figure 4 This is a schematic diagram of the installation of the heat exchange tube and the elastic baffle of the present invention; Figure 5 This is a schematic diagram of the structure of the elastic baffle of the present invention; Figure 6 This is a schematic diagram of the cooperation between the elastic baffle and the limiting pin of the present invention; Figure 7 This is a schematic diagram of the flow path of the low-temperature molten salt in the molten salt tube of the present invention.

[0019] Legend: 1. Shell; 11. Hydrothermal inlet; 12. Hydrothermal outlet; 13. Fixing plate one; 14. Fixing plate two; 15. Molten salt inlet pipe; 16. Molten salt outlet pipe; 2. Molten salt tube; 21. Limit pin; 3. Heat exchanger tube; 31. Heat-conducting fin; 32. Circular plate; 33. Tension spring; 34. Telescopic protective tube; 4. Elastic spoiler; 41. Mounting ring. Detailed Implementation

[0020] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1: Please refer to Figures 1-7As shown, in the case of solar thermal power plants under peak-shaving conditions, traditional molten salt heat exchangers have fixed flow direction and non-adjustable turbulence structure. Molten salt is prone to forming flow stagnation layers and flow dead zones on the tube wall contact surface, resulting in local overheating of molten salt on three sides of the heat exchange tube, uneven heating of molten salt on two sides of the molten salt tube, and inability to adapt to flow fluctuations. Low-flow-rate molten salt is prone to decomposition, and high-flow-rate heat exchange time is insufficient, resulting in low heat exchange uniformity and low heat exchange efficiency under varying operating conditions. The following solutions can be used to solve these problems. This embodiment of a high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence includes a shell 1, with a hot liquid inlet 11 and a hot liquid outlet 12 fixedly connected to both ends of the shell 1, and a fixing plate 13 fixedly installed on both sides inside the shell 1.

[0022] Molten salt pipes 2 are installed between fixed plates 13 and multiple of them are provided. An insulation layer is installed between fixed plates 13 and outside the molten salt pipes 2. The insulation layer covers the outer space of the molten salt pipes 2 inside the shell 1, reduces the heat loss of the shell 1 to the outside, reduces ineffective heat loss, ensures the overall temperature level of the molten salt in the molten salt pipes 2, and externally assists in suppressing the tendency of molten salt crystallization induced by local temperature drop of the pipe wall, so as to realize the basic function of distributed passive heat tracing.

[0023] The heat exchange tube 3 is located inside the corresponding molten salt tube 2 and is coaxially arranged with it. Multiple heat-conducting plates 31 are fixedly connected to the outer wall of the heat exchange tube 3 along its length. The heat-conducting plates 31 are 180° twisted spiral blades. Two sets of heat-conducting plates 31 are arranged in an array along the annular outer wall of the heat exchange tube 3. The heat-conducting plates 31 are slidably connected to the inner wall of the molten salt tube 2.

[0024] The heat exchange tube 3 utilizes the heat-conducting plate 31 to further increase the heat exchange area and guide the low-temperature molten salt to swirl around the heat exchange tube 3, extending the heat exchange path. The spiral curved surface of the heat-conducting plate 31 guides the low-temperature molten salt to form a swirling flow around the heat exchange tube 3, passively lengthening the molten salt flow heat exchange path and extending the heat exchange contact time. Subsequently, the reverse swirling structure counteracts this, weakening the basic conditions for the formation of the stagnant layer on the tube wall from the structural foundation.

[0025] Multiple elastic baffles 4 are arranged along the length of the heat exchange tube 3. The heat conduction plate 31 is located between two adjacent sets of elastic baffles 4. The elastic baffles 4 are also 180° twisted spiral blades. The heat conduction plate 31 and the elastic baffles 4 rotate in opposite directions. The two are staggered along the circumference of the heat exchange tube 3.

[0026] The thickness of the elastic baffle 4 continuously increases along the flow direction of the low-temperature molten salt. The thick end of the elastic baffle 4 has a circular arc cone structure. The circular arc cone structure at the thick end can disperse the fluid impact stress and avoid root fatigue fracture caused by long-term alternating stress of the elastic baffle 4, thereby improving the long-term operational reliability of the adaptive deformation structure. Multiple mounting rings 41 are rotatably installed on the outer wall of the heat exchange tube 3 and are rotatably connected to the corresponding elastic baffle 4. Limiting pins 21 are fixedly installed on the molten salt tube 2 at the corresponding mounting rings 41. The limiting pins 21 abut against the arc-shaped convex side of the corresponding elastic baffle 4, restricting the overall side tilting and deflection of the elastic baffle 4, allowing only axial compression deformation, guiding the low-temperature molten salt between the two adjacent sets of heat conduction plates 31 to swirl in the opposite direction, so that the low-temperature molten salt turbulent mixing improves the heat exchange uniformity, while impacting the scale inside the molten salt tube 2 for self-cleaning.

[0027] Inside the shell 1, a second fixing plate 14 is fixedly installed on the opposite side of the two sets of fixing plates 13. A liquid injection chamber is formed between the first fixing plate 13 and the second fixing plate 14 on the side of the hydrothermal inlet 11, and a liquid outlet chamber is formed between the first fixing plate 13 and the second fixing plate 14 on the side of the hydrothermal outlet 12. Both the liquid injection chamber and the liquid outlet chamber are connected to the molten salt pipe 2.

[0028] A molten salt inlet pipe 15 communicating with the injection chamber is fixedly installed at the bottom of the shell 1, and a molten salt outlet pipe 16 communicating with the outlet chamber is fixedly installed at the top of the shell 1.

[0029] The heat exchange tube 3 is slidably connected to two sets of fixed plates 14. The fixed plates 14 are fitted with sealing rings that slide with the heat exchange tube 3 to prevent molten salt leakage. The heat exchange tube 3 and the fixed plates 14 can only move axially and do not rotate. The hot liquid inlet 11 and the fixed plates 14 form a hot liquid inlet chamber, and the hot liquid outlet 12 and the corresponding fixed plates 14 form a hot liquid outlet chamber. The heat exchange tube 3 is connected to the hot liquid inlet chamber and the hot liquid outlet chamber.

[0030] During operation, the hydrothermal medium enters the hydrothermal inlet chamber through the hydrothermal inlet 11, disperses into each heat exchange tube 3 for heat exchange, and after heat exchange, it flows into the hydrothermal outlet chamber and is discharged from the hydrothermal outlet 12; the low-temperature molten salt enters the annular gap between the molten salt tube 2 and the heat exchange tube 3 through the molten salt inlet pipe 15 and the injection chamber, wraps around the heat exchange tube 3 to complete heat absorption, and the high-temperature molten salt after heating gathers into the outlet chamber and is sent out by the molten salt outlet pipe 16.

[0031] Cross-swirling heat transfer process: During the flow of low-temperature molten salt, it first impacts the elastic turbulence plate 4 to form a positive spiral swirling flow. When it flows through the heat-conducting plate 31 with the opposite swirling direction and circumferential misalignment, the fluid is forced to turn and form a reverse spiral swirling flow.

[0032] Two sets of blades arranged alternately along the axis continuously cut and mix the molten salt, actively flushing and breaking the flow stagnation layer on the contact surfaces of the outer wall of heat exchange tube 3 and the inner wall of molten salt tube 2, eliminating dead zones in the flow inside the tube, and avoiding uneven heating and cooling problems such as local overheating of molten salt around heat exchange tube 3 and insufficient heating of molten salt near the inner wall of molten salt tube 2.

[0033] When the elastic baffle 4 is impacted by the flow of low-temperature molten salt, it undergoes compression deformation along the length of the heat exchange tube 3. Under different pressure forces, it exists in three working states with different compression amounts: medium-pressure flow, low-pressure smooth flow, and high-pressure slow flow. The compression length of the elastic baffle 4 when it is in medium-pressure flow is greater than the compression length when it is in low-pressure smooth flow, but less than the compression length when it is in high-pressure slow flow.

[0034] Preset medium pressure state: When the low temperature molten salt flows at a set flow rate, it generates a medium axial thrust on the elastic baffle 4. The elastic baffle 4 is moderately compressed and the free end bends outward in an arc shape. The pitch decreases and enters the medium pressure flow state, which moderately prolongs the residence time of the molten salt to ensure sufficient and stable heat exchange. The thrust synchronously drives the heat exchange tube 3 to move downstream of the molten salt. Low pressure and low flow rate state: The impact force is reduced, the compression of the elastic baffle 4 is reduced, and it rebounds inward in an arc shape due to its own elasticity. The pitch increases and the throttling resistance is reduced, forming a low pressure smooth flow mode, which accelerates the flow rate of molten salt and avoids the medium from staying in the high temperature for a long time and decomposing.

[0035] Under high pressure and high flow rate conditions: the impact force is further increased, the compression of the elastic baffle 4 is further increased, and the pitch is further narrowed, forming a high pressure slow flow mode, which slows down the molten salt flow rate and makes up for the deficiency of insufficient heat exchange time under high flow rate.

[0036] By relying on the spiral heat-conducting plates 31 arranged in opposite directions and circumferentially staggered, and the elastic turbulence plates 4, a counter-current swirling flow field is formed, which actively breaks the flow stagnation layer on the pipe wall, eliminates the heat exchange dead zone, and solves the problem of uneven heat exchange. At the same time, the heat-conducting plates 31 increase the heat exchange area and extend the flow path to improve the basic heat exchange capacity.

[0037] The elastic turbulence plate 4 with a gradually varying thickness structure can autonomously switch between three working states: low-pressure smooth flow, medium-pressure diversion, and high-pressure slow flow, based on the impact force of the low-temperature molten salt flow. It can adapt to the frequent flow fluctuations of solar thermal power plants without the need for an external power source. The low flow velocity prevents molten salt decomposition, and the high flow velocity ensures sufficient heat absorption. The overall heat exchange uniformity, operational stability, and comprehensive heat exchange efficiency are significantly better than those of traditional fixed turbulence structures.

[0038] Example 2: Please refer to Figure 1 , Figure 3 and Figure 4As shown, the following solutions address the problem that molten salt heat exchangers are prone to scale and impurity deposits on the tube walls during long-term operation. The scale layer continuously thickens, increasing the heat transfer resistance and causing the heat exchange efficiency to decline year by year. It can also lead to increased flow resistance inside the tubes, local tube blockage, or even molten salt freezing and shutdown. Furthermore, there is a lack of an online continuous self-cleaning scale synergy structure. In this embodiment, a circular plate 32 is fixedly connected to one end of the heat exchange tube 3 at the hydrothermal outlet 12, and a tension spring 33 is fixedly connected between the circular plate 32 and the corresponding fixed plate 14. A telescopic protective tube 34 is fixedly connected to the outside of the tension spring 33. The telescopic protective tube 34 is a telescopic and sealed sleeve structure that completely covers the external space of the tension spring 33.

[0039] When the flow rate of the low-temperature molten salt fluctuates, it causes the magnitude of the axial thrust of the low-temperature molten salt on the heat-conducting plate 31 and the elastic baffle plate 4 to change synchronously, thereby driving the entire reciprocating descaling mechanism to operate continuously. During the flow rate increase phase: the axial thrust increases, pushing the heat exchange tube 3 to move horizontally in the direction of molten salt flow and stretching the tension spring 33. The outer edge of the heat-conducting plate 31 fixed on the outer wall of the heat exchange tube 3 is always in close contact with the inner wall of the molten salt tube 2, continuously scraping away the salt scale and metal oxide deposits that are gradually deposited on the tube wall, preventing the scale layer from hardening and blocking heat transfer.

[0040] During the flow rate reduction phase: the fluid thrust decreases, the axial thrust decreases, the stretched spring 33 retracts due to its own elasticity, pulling the heat exchange tube 3 to move in the opposite direction to reset, the heat conduction plate 31 scrapes the tube wall twice during the return stroke, and then, with the help of the flow rate fluctuation, reciprocating continuous mechanical scraping is achieved.

[0041] The reciprocating stroke of the heat exchange tube 3 is designed to match the stiffness of the tension spring 33 with the amplitude of the molten salt flow rate fluctuation, so as to avoid the problem of the heat exchange tube 3 sliding over the stroke and hitting the shell 1.

[0042] The elastic baffle plate 4 descaling by stress: During the heat exchange cycle, the elastic baffle plate 4 is repeatedly compressed, rebounded and bent, and its arc-shaped side continuously bears the periodic bending stress. The scale attached to the arc surfaces on both sides of the elastic baffle plate 4 cracks, peels off and falls off due to the repeated stress, so as to realize the synchronous self-cleaning of the elastic baffle plate 4 and avoid the scale on the surface of the elastic baffle plate 4 from changing the original turbulent flow field morphology.

[0043] Venturi jet impact-assisted descaling: During the reciprocating translation of the heat exchange tube 3, the limiting pin 21 constrains the outer convex side of the elastic baffle 4, and in conjunction with the rotating assembly relationship of the mounting ring 41, the elastic baffle 4 produces a small forward and reverse deflection, dynamically adjusting the circumferential misalignment angle between the elastic baffle 4 and the heat conduction plate 31; at the same time, the setting of the mounting ring 41 makes the gap between its outer wall and the inner wall of the molten salt tube 2 smaller than the gap between the heat exchange tube 3 and the molten salt tube 2, the gap contraction forms a Venturi acceleration effect, and the local sudden increase in molten salt flow velocity forms a rapid jet effect, which washes away the fine adhering impurities on the outer wall of the heat exchange tube 3 and the surface of the heat conduction plate 31, and removes the scale.

[0044] Relying on the axial thrust generated by the fluctuation of molten salt flow rate, combined with the reset elastic force of tension spring 33, the heat exchange tube 3 is driven to slide back and forth, constructing a multi-synergistic self-cleaning system of mechanical scraping, elastic baffle 4 deformation stress self-peeling, and Venturi effect jet flushing. This system can continuously inhibit the accumulation of salt scale on the tube wall, slow down the rate of heat exchanger efficiency decay, effectively avoid the risk of increased pipeline flow resistance and local pipe blockage caused by scaling, reduce equipment operation and maintenance costs, and extend the continuous and stable service life of the heat exchanger.

[0045] Example 3: Please refer to Figures 1-7 As shown, the present invention also proposes a method for using a high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence, comprising the following steps: Step 1: The hydrothermal medium enters multiple heat exchange tubes 3 through the hydrothermal inlet 11 and the hydrothermal inlet chamber, and then exits from the hydrothermal outlet chamber and the hydrothermal outlet 12. Low-temperature molten salt enters the area between multiple molten salt tubes 2 and heat exchange tubes 3 through the molten salt inlet pipe 15 and the injection chamber, and wraps around the corresponding heat exchange tubes 3. After heat exchange, high-temperature molten salt is formed and discharged from the outlet chamber and the molten salt outlet pipe 16. Step Two: Molten Salt Cross-Swirl Heat Exchange to Enhance Heat Exchange Uniformity and Area: When the low-temperature molten salt flows inside the molten salt tube 2, it first impacts the elastic baffles 4 to form a positive spiral swirling flow. When it flows through the twisted spiral heat-conducting plates 31 arranged in opposite directions and circumferentially staggered, the fluid is forced to turn to form a reverse spiral swirling flow. Multiple sets of alternating elastic baffles 4 and heat-conducting plates 31 along the axial direction of the heat exchange tube 3 continuously divide, cut, cross-swirl, and mix the molten salt, eliminating the flow stagnation layer on the tube wall contact surface and preventing local overheating of the low-temperature molten salt in the outer wall area of ​​the heat exchange tube 3 and insufficient heating of the low-temperature molten salt in the inner wall area of ​​the molten salt tube 2. At the same time, the heat exchange area of ​​the heat exchange tube 3 is further increased by the heat-conducting plates 31, which further enhances the heating effect of the low-temperature molten salt heat exchange. Step 3: Medium-pressure flow, the elastic baffle 4 is compressed and deformed to enter the medium-pressure flow state: the low-temperature molten salt flows inside the molten salt tube 2 at a set flow rate. The fluid continuously impacts the concave side of the elastic baffle 4 to generate axial thrust, and this thrust is set as medium pressure. With the help of the limiting pin 21 on the inner wall of the low-temperature molten salt tube 2, the elastic baffle 4 is resisted by the convex side, which restricts the deflection of the elastic baffle 4. Under the medium-pressure thrust, the elastic baffle 4 is compressed and deformed along the length of the heat exchange tube 3. The elastic baffle 4 generates a corresponding compression amount, and the free end bends towards its own arc-shaped convex side. The pitch of the free end decreases, forming a medium-pressure flow state. The residence time of the low-temperature molten salt in the molten salt tube 2 is appropriately extended to ensure sufficient heat exchange between the molten salt and the tube wall. At the same time, the axial thrust pushes the heat exchange tube 3 to move in the direction of low-temperature molten salt flow and stretches the tension spring 33. Step 4: Adaptive adjustment of molten salt flow rate fluctuations, switching between low-pressure smooth flow and high-pressure slow flow operating states: If the molten salt flow rate decreases, the thrust formed by the elastic baffle plate 4 and the heat-conducting plate 31 along the length of the heat exchange tube 3 will decrease. This thrust, which is less than the medium pressure, will be set as the low pressure. The axial compression of the elastic baffle plate 4 will decrease simultaneously. With its own elasticity, the free end of the elastic baffle plate 4 will rebound towards the concave side of the arc. As the low pressure thrust decreases, the rebound degree will increase in the opposite direction. The pitch of the free end of the elastic baffle plate 4 will increase, the turbulence and throttling effect will be weakened, the flow resistance of the low-temperature molten salt will decrease, the flow rate will increase, and the smooth flow effect of rapid flow will be achieved, avoiding overheating. If the molten salt flow rate increases, the thrust formed by the elastic baffle plate 4 and the heat-conducting plate 31 along the length of the heat exchange tube 3 will increase. This thrust, which is greater than the medium pressure, will be set as the high pressure. The elastic baffle plate 4 will be further axially compressed, the free end will bend more towards the arc-shaped outward convex side, the pitch will be further reduced, the turbulence and throttling effect will be enhanced, the molten salt flow rate will be slowed down, and a high slow flow effect will be achieved to ensure sufficient heating. Step 5: Self-cleaning scale removal: The flow rate of the low-temperature molten salt fluctuates. When the flow rate decreases, under the tension of the tension spring 33, the heat exchange tube 3, carrying the elastic baffle 4 and the heat-conducting plate 31, moves in the opposite direction of the low-temperature molten salt flow. When the flow rate increases, the heat exchange tube 3, carrying the elastic baffle 4 and the heat-conducting plate 31, moves further in the direction of the low-temperature molten salt flow. Through the movement of the heat exchange tube 3, the elastic baffle 4 and the heat-conducting plate 31 scrape off the scale on the inner wall of the molten salt tube 2. By utilizing the compression and rebound bending of the elastic baffle 4, the scale on its own curved side surface is subjected to extrusion-type self-crushing and peeling treatment. Furthermore, the rotational connection of the mounting ring 41 and the fixing of the position of the limiting pin 21, combined with the thrust of the low-temperature molten salt on the concave side of the elastic baffle 4, cause the heat exchange tube 3 to reciprocate during the flow rate fluctuation process, resulting in the elastic baffle 4 deflecting in both directions. This changes the offset angle between the elastic baffle 4 and the heat conduction plate 31, as well as the small gap between the mounting ring 41 and the side wall of the molten salt tube 2, achieving a localized Venturi effect. This allows the low-temperature molten salt to impact different areas of the heat conduction plate 31, assisting in the impact-type detachment of the heat conduction plate 31 from the scale on the surface of the heat exchange tube 3.

[0046] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence, characterized in that, Includes a shell (1), with a hydrothermal inlet (11) and a hydrothermal outlet (12) fixedly connected at both ends of the shell (1), and a fixing plate (13) fixedly installed on both sides inside the shell (1). Molten salt pipes (2) are installed between fixed plates (13) and multiple of them are provided. An insulation layer is installed between the fixed plates (13) and on the outside of the molten salt pipes (2). The heat exchange tube (3) is located inside the corresponding molten salt tube (2) and is coaxial with it. Multiple heat-conducting plates (31) are fixedly connected to the outer wall of the heat exchange tube (3) along its length direction. The heat exchange tube (3) uses the heat-conducting plates (31) to further increase the heat exchange area and guide the low-temperature molten salt to swirl around the heat exchange tube (3) to extend the heat exchange path. Elastic baffles (4) are arranged in multiple ways along the length of the heat exchange tube (3). The heat-conducting plates (31) are located between two adjacent sets of elastic baffles (4), guiding the low-temperature molten salt between the two adjacent sets of heat-conducting plates (31) to reverse the swirling flow, so that the low-temperature molten salt turbulent mixing improves the heat exchange uniformity, while impacting the scale inside the molten salt tube (2) for self-cleaning. When the elastic baffle (4) is impacted by the flow of low-temperature molten salt, it undergoes compression deformation along the length of the heat exchange tube (3) and has three different compression states under different pressure forces: medium-pressure flow, low-pressure smooth flow, and high-pressure slow flow.

2. The high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 1, characterized in that, The shell (1) is fixedly installed with a second fixing plate (14) on the opposite side of the two sets of fixing plates (13). A liquid injection chamber is formed between the first fixing plate (13) and the second fixing plate (14) on the side of the hydrothermal inlet (11), and a liquid outlet chamber is formed between the first fixing plate (13) and the second fixing plate (14) on the side of the hydrothermal outlet (12). Both the liquid injection chamber and the liquid outlet chamber are connected to the molten salt pipe (2).

3. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 2, characterized in that, The bottom of the housing (1) is fixedly installed with a molten salt inlet pipe (15) communicating with the injection chamber, and the top of the housing (1) is fixedly installed with a molten salt outlet pipe (16) communicating with the outlet chamber.

4. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 2, characterized in that, The heat exchange tube (3) is slidably connected to two sets of fixed plates (14). A hot liquid inlet cavity is formed between the hot liquid inlet (11) and the fixed plate (14). A hot liquid outlet cavity is formed between the hot liquid outlet (12) and the corresponding fixed plate (14). The heat exchange tube (3) is connected to the hot liquid inlet cavity and the hot liquid outlet cavity.

5. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 1, characterized in that, Both the heat-conducting plate (31) and the elastic baffle plate (4) are 180° twisted spiral blades. The heat-conducting plate (31) and the elastic baffle plate (4) rotate in opposite directions. Both the heat-conducting plate (31) and the elastic baffle plate (4) are arranged in two arrays along the annular outer wall of the heat exchange tube (3), and the heat-conducting plate (31) and the elastic baffle plate (4) are staggered along the circumference of the heat exchange tube (3).

6. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 1, characterized in that, The heat-conducting plate (31) is slidably connected to the inner wall of the molten salt tube (2), the elastic baffle plate (4) is slidably connected to the molten salt tube (2) and the heat exchange tube (3), and a plurality of mounting rings (41) are rotatably installed on the outer wall of the heat exchange tube (3) and rotatably connected to the corresponding elastic baffle plate (4).

7. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 6, characterized in that, Limiting pins (21) are fixedly installed on the molten salt tube (2) and at the corresponding mounting ring (41). The limiting pins (21) abut against the arc-shaped convex side of the corresponding elastic baffle (4).

8. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 7, characterized in that, The thickness of the elastic baffle (4) increases continuously along the flow direction of the low-temperature molten salt, and the thick end of the elastic baffle (4) has a circular arc cone structure.

9. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence as described in claim 8, characterized in that, The compression length of the elastic baffle (4) during medium-pressure flow is greater than that during low-pressure smooth flow, but less than that during high-pressure slow flow.

10. A high-efficiency molten salt heat exchanger with built-in distributed heat tracing and turbulence according to claim 2, characterized in that, The heat exchange tube (3) is fixedly connected to a circular plate (32) at one end of the hot liquid outlet (12), and a tension spring (33) is fixedly connected between the circular plate (32) and the corresponding fixed plate (14), and a telescopic protective tube (34) is fixedly connected to the outside of the tension spring (33).

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