A vacuum plate heat exchanger

Abstract

The present application relates to the field of heat exchange, and discloses a vacuum plate heat exchanger, which comprises a main heat exchange box, a flow collecting pipe and a flow collecting box and a lower heat exchange box, the lower heat exchange box is internally provided with heat exchange plates storing phase change fluid, the top of the heat exchange plates is provided with a first opening and a second opening, the main heat exchange cavity is internally provided with heat exchange pipes, the heat exchange pipes are internally provided with flowing fluid to be exchanged, the flow collecting box comprises an upper gas flow collecting box and a backflow flow collecting box, the flow collecting pipe comprises an upper gas flow collecting pipe and a backflow flow collecting pipe, the flow collecting cavity of the upper gas flow collecting box is communicated with the main heat exchange cavity through the upper gas flow collecting pipe, the flow collecting cavity of the backflow flow collecting box is communicated with the bottom of the main heat exchange cavity through the backflow flow collecting pipe, and the top of the thin plate is welded to the bottom of the flow collecting box, so that the first opening is communicated with the flow collecting cavity of the upper gas flow collecting box, and the second opening is communicated with the flow collecting cavity of the backflow flow collecting box. The above-mentioned vacuum plate heat exchanger separates the gas-liquid flow channel of the phase change material, realizes efficient circulation of the phase change material, and has good heat exchange effect.

Description

Technical Field

[0001] This invention relates to the field of heat exchange, and more particularly to a vacuum plate heat exchanger. Background Technology

[0002] In industrial production, utilizing flue gas for heat exchange with fluids is an important technical means to recover waste heat from flue gas and reduce energy consumption. Among these technologies, vacuum plate heat exchangers are commonly used because the vacuum environment can lower the boiling point of fluids and enhance phase change heat transfer. For example, Chinese patent application CN119934870A discloses a vacuum plate heat exchanger, which includes an upper heat exchange chamber and a lower heat exchange chamber that are isolated from each other. The upper heat exchange chamber contains multiple heat exchange tubes, and the lower heat exchange chamber contains multiple heat exchange plates arranged at intervals. There is a flue gas passage between two adjacent heat exchange plates. The heat exchange plates contain a first flow chamber for storing phase change material. The heat exchange tubes in the upper heat exchange chamber contain the fluid to be heat exchanged, and the heat exchange tubes contain a second flow chamber. The second flow chamber is connected to the first flow chamber in the corresponding heat exchange plate through a transition structure. The heat exchange process is as follows: the high-temperature flue gas first exchanges heat with the phase change material inside the heat exchange plate, causing the phase change material to absorb heat and change from a liquid to a gaseous state; then the gaseous phase change material exchanges heat a second time with the heat exchange tube, transferring heat to the fluid flowing outside the heat exchange tube, ultimately completing the indirect recovery and utilization of the flue gas waste heat. However, in the above heat exchange method, the rising gaseous phase change material and the falling liquid phase change material are prone to collision, resulting in low circulation efficiency and affecting the heat exchange effect. Summary of the Invention

[0003] To address the aforementioned technical problem of poor circulation of phase change materials, this invention provides a vacuum plate heat exchanger that separates the gas-liquid flow channels of the phase change material, thereby achieving efficient circulation of the phase change material.

[0004] The specific technical solution of this invention is as follows: A vacuum plate heat exchanger includes an upper heat exchange assembly and a lower heat exchange box. The lower heat exchange box has a lower heat exchange cavity and multiple sets of heat exchange plates spaced apart within the lower heat exchange cavity. A flue gas channel for flue gas circulation is formed between two adjacent sets of heat exchange plates. The heat exchange plates are welded together by two thin plates arranged front and back and several welded parts. The unwelded parts of the heat exchange plates are far apart to form several first flow cavities that are interconnected at the bottom. The top of the heat exchange plates has a first opening and a second opening that communicate with the first flow cavities. A phase change fluid is provided in the first flow cavities. The upper heat exchange assembly includes a main heat exchange box with a main heat exchange cavity, a manifold, and a manifold box with a manifold cavity. The main heat exchange box, manifold, and manifold box are formed by... The components are arranged sequentially from top to bottom. The main heat exchange chamber contains heat exchange tubes, and the heat exchange tubes contain a second flow chamber for the flow of the fluid to be heat exchanged. The manifold extends along the arrangement direction of the multiple heat exchange plates. The manifold box includes an upper gas manifold box and a return manifold box. The manifold pipe includes an upper gas manifold pipe and a return manifold pipe. The manifold chamber of the upper gas manifold box is connected to the main heat exchange chamber through the upper gas manifold pipe. The manifold chamber of the return manifold box is connected to the bottom of the main heat exchange chamber through the return manifold pipe. The height of the position where the upper gas manifold pipe is connected to the main heat exchange chamber is higher than the height of the position where the return manifold pipe is connected to the main heat exchange chamber. The top of the thin plate is welded to the bottom of the manifold box so that the first opening is connected to the manifold chamber of the upper gas manifold box and the second opening is connected to the manifold chamber of the return manifold box.

[0005] In the aforementioned vacuum plate heat exchanger, flue gas is introduced into the lower heat exchange chamber, and the first flow chamber of the heat exchange plate is filled with liquid phase change fluid. The flue gas exchanges heat with the phase change fluid, causing the phase change fluid to change from a liquid state to a gaseous state. The gaseous phase change fluid flows through the first opening, the upper gas manifold box, and the upper gas manifold pipe to the main heat exchange chamber, transferring heat to the heat exchange tubes, and then transferring the temperature to the fluid to be heat exchanged in the heat exchange tubes, achieving efficient heat exchange. After heat exchange, the temperature of the phase change fluid decreases, and it becomes liquid again. It then falls back into the first flow chamber through the return manifold pipe, the return manifold box, and the second opening. This cycle indirectly transfers the heat of the flue gas to the fluid to be heat exchanged. In this vacuum plate heat exchanger, the first opening, the upper gas manifold box, and the upper gas manifold pipe form a dedicated airflow channel for the gaseous phase change fluid to enter the main heat exchange chamber. The return manifold pipe, the return manifold box, and the second opening form a dedicated liquid flow channel for the condensed liquid phase change fluid to fall back into the first flow chamber. This separation design of the gas and liquid flow channels eliminates gas-liquid flow conflicts. Furthermore, combined with the height difference design between the upper gas manifold pipe and the return manifold pipe, gravity is used to further enhance the reflux force of the liquid phase change fluid, achieving efficient circulation of the phase change material and ensuring stable and efficient heat exchange. In addition, the top of the thin plate is welded to the bottom of the manifold box, achieving a sealed connection between the heat exchange plate and the manifold box. This invention achieves a sealed connection between multiple first flow chambers and the manifold box through a single centralized welding of the heat exchange plate and the main heat exchange box. This results in fewer welding points, lower welding quality control difficulty, high welding quality, less leakage of heat exchange fluid, and high heat exchange efficiency. In terms of structural design, heat exchange tubes that do not require welding are placed in the main heat exchange chamber, and the fluid to be exchanged is placed inside the heat exchange tubes. The fluid to be exchanged is not easy to leak, and the gaseous phase change fluid is not easy to enter the heat exchange tubes. At the same time, the gaps between the heat exchange plates are used as flue gas channels to reduce the leeward area, reduce the degree of ash accumulation, and ensure stable heat exchange efficiency.

[0006] Optionally, the heat exchange plate is provided with a vertically extending partition welding part, which divides the first flow cavity in the heat exchange plate into a first cavity and a second cavity. The bottom of the first cavity and the second cavity are connected and the top is isolated. A first opening is provided at the top of the first cavity and is connected to the first cavity, and a second opening is provided at the top of the second cavity and is connected to the second cavity.

[0007] In the above technical solution, when the liquid phase change fluid falls back into the second cavity through the second opening, it will automatically flow to the first cavity along the bottom area connecting the two cavities under the action of gravity and the fluid's own fluidity, so as to achieve uniform distribution of the phase change fluid in the entire heat exchange plate, avoid the problem of wasted heat exchange area or reduced heat exchange efficiency due to insufficient local fluid, and the liquid enters from the bottom to avoid conflict with the rising gas, ensuring smooth circulation.

[0008] Optionally, the first cavity is located near the flue gas inlet, and the second cavity is located near the flue gas outlet.

[0009] In the above technical solution, the flue gas carries the most heat when it first enters the equipment. As it flows along the flue gas channel, it gradually releases heat. By the time it reaches the flue gas outlet side, the temperature has decreased. The liquid phase change fluid falling back into the second chamber can be in a relatively low-temperature flue gas environment. This effectively prevents the liquid phase change fluid from being reheated and vaporized due to contact with high-temperature flue gas during the recirculation process. This also prevents it from turning into a gaseous state again in the dedicated liquid flow channel and returning to the main heat exchange chamber. This also prevents the liquid phase change fluid from absorbing heat and vaporizing during the recirculation process, and prevents the phase change material that turns into a gaseous state again from affecting the recirculation of the liquid phase change fluid, thus ensuring the efficient circulation of the phase change material.

[0010] Optionally, the length of the first cavity in the flue gas flow direction is greater than the length of the second cavity in the flue gas flow direction.

[0011] In the above technical solution, by extending the length of the first cavity in the flue gas flow direction, the longer contact path allows the phase change fluid to absorb the heat released by the flue gas more fully, improving the gasification efficiency and providing a more sufficient heat energy carrier for the subsequent heat exchange between the main heat exchange cavity and the fluid to be exchanged. By shortening the length of the second cavity, excessive ineffective heat exchange area can be avoided in the low-temperature region, thereby improving the energy conversion efficiency of the entire heat exchange system.

[0012] Optionally, the main heat exchange box is cylindrical.

[0013] In the above technical solution, when the gaseous phase change fluid releases heat and condenses into a liquid state in the main heat exchange chamber, the smooth arc-shaped inner wall of the cylinder can replace the additional flow guiding component, guiding the liquid phase change fluid to slide naturally along the inner wall to the central area at the bottom of the chamber and converge. The converged liquid phase change fluid can flow into the return manifold quickly and smoothly under the action of gravity, improving circulation efficiency and reducing dead zones of liquid accumulation.

[0014] Optionally, the top of the upper air manifold extends into the main heat exchange chamber and protrudes from the inner wall of the main heat exchange box.

[0015] In the above technical solution, when the gaseous phase change fluid is transported to the main heat exchange chamber through the upper gas manifold, the gas can diffuse more fully into the internal space of the main heat exchange chamber, enhancing the heat exchange efficiency. In addition, the upper gas manifold opening protrudes from the inner wall and the connection position is higher than the return manifold, making it difficult for the liquid fluid to rise to the height of the opening and enter the interior of the upper gas manifold, maintaining strict separation of the gas and liquid flow channels and ensuring the stability and smoothness of the phase change fluid circulation.

[0016] Optionally, the manifold of the upper manifold is connected to the manifold of the return manifold; or, the manifold of the upper manifold is isolated from the manifold of the return manifold.

[0017] In the above technical solution, the upper gas manifold and the return manifold are connected, meaning that the upper gas manifold and the return manifold share the same manifold, simplifying the equipment structure and reducing costs. When the upper gas manifold and the return manifold are isolated, the upper gas manifold is only used to transport gaseous phase change fluid, and the return manifold is only used to return liquid phase change fluid. There is no fluid exchange channel between the two, ensuring that the gas and liquid two-phase fluids flow stably along their respective paths. In addition, the isolation design also facilitates independent monitoring and control of the pressure and flow rate of the gas and liquid two-phase fluids, making it suitable for scenarios with high heat exchange accuracy requirements and strict control of fluid state.

[0018] Optionally, the number of upper air manifolds is greater than the number of return air manifolds.

[0019] In the above technical solutions, gaseous phase change fluids have a larger intermolecular distance and a higher volume ratio, requiring more space in the flow channel. Increasing the number of upper gas manifolds can significantly widen the flow cross-section of the gaseous fluid, reduce the resistance during gas flow, and ensure that the gaseous phase change fluid enters the main heat exchange chamber quickly and uniformly. In contrast, liquid phase change fluids have denser molecules and smaller volumes, requiring only a few return manifolds to meet their flow requirements. Furthermore, the core function of the return manifold is to transport the condensed liquid fluid, rather than to participate in heat exchange. Reducing the number of return manifolds can reduce the heat exchange area of ​​the liquid return section.

[0020] Optionally, the main heat exchange box includes multiple mutually isolated main heat exchange chambers, each main heat exchange chamber is provided with multiple heat exchange plates, and each heat exchange plate is only connected to the corresponding main heat exchange chamber.

[0021] In the above technical solution, multiple heat exchange plates and multiple isolated main heat exchange chambers form independent heat exchange units, preventing structural failures in one unit from affecting the operation of the entire equipment. Furthermore, the fault is confined to the unit and will not spread to other independent units. Regarding the leakage process, if a unit leaks, its internal phase change fluid will be discharged through the leak point. However, because the phase change fluid in each unit circulates only in its own closed loop without external replenishment, the leakage will naturally stop once the fluid in that unit has completely leaked, preventing the loss of phase change fluid to other units. The flue gas passage in the lower heat exchange box is under negative pressure, making it difficult for flue gas to reverse and enter the main heat exchange chamber through the leak point. Simultaneously, the heat exchange tubes themselves have anti-corrosion properties, so even if a small amount of flue gas enters the faulty unit, it is unlikely to damage the heat exchange tubes, thus achieving precise control of fault risk.

[0022] Optionally, the upper heat exchange assembly includes multiple mutually isolated main heat exchange boxes, each main heat exchange box is provided with multiple manifolds, and the manifolds corresponding to different main heat exchange boxes are mutually isolated. The manifolds are connected to the corresponding main heat exchange boxes through corresponding manifolds. Each main heat exchange chamber is provided with multiple heat exchange plates, and the heat exchange plates are connected to the corresponding manifolds.

[0023] In the above technical solution, the heat exchange plate, the corresponding manifold box, and the main heat exchange box form independent heat exchange units, preventing structural failures in one unit from affecting the operation of the entire equipment. Furthermore, the flow channels, pipes, and heat exchange plates of each unit are completely independent and have no common manifold, so when a unit needs maintenance, there is no need to shut down the entire system. In addition, each main heat exchange box can be designed with independent parameters, offering high flexibility.

[0024] Compared with the prior art, the present invention has at least the following advantages: (1) In this vacuum plate heat exchanger, the first opening, the upper gas manifold box and the upper gas manifold pipe form a dedicated airflow channel for gaseous phase change fluid to enter the main heat exchange chamber. The return manifold pipe, the return manifold box and the second opening form a dedicated liquid flow channel for condensed liquid phase change fluid to fall back into the first flow chamber. This gas-liquid flow channel separation design eliminates gas-liquid flow conflict. At the same time, combined with the height difference design between the upper gas manifold pipe and the return manifold pipe, the return flow power of the liquid phase change fluid is further enhanced by gravity, realizing efficient circulation of phase change material and ensuring stable and efficient heat exchange efficiency. (2) In the overall design of heat exchange equipment, heat exchange margin is usually set in advance to cope with the fluctuation of operating conditions. However, this solution uses multiple independent heat exchange units to form a complete heat exchange structure. Even if a small number of heat exchange units stop operating due to failure, the remaining normally operating heat exchange units can still ensure that the total heat exchange of the entire equipment meets the heat exchange requirements of production. (3) By extending the length of the first cavity in the flue gas flow direction, a longer contact path is created for the phase change fluid and the high-temperature flue gas, allowing the phase change fluid to absorb the heat released by the flue gas more fully, significantly improving the gasification efficiency. This provides a more sufficient heat energy carrier for the subsequent heat exchange between the main heat exchange chamber and the fluid to be exchanged. At the same time, increasing the number of upper gas manifolds can effectively widen the flow cross-section of the gaseous fluid, reduce gas flow resistance, and ensure that the gasified phase change fluid can enter the main heat exchange chamber quickly and smoothly. In addition, shortening the length of the second cavity can avoid setting too much ineffective heat exchange area in the area where the flue gas temperature has been significantly reduced, reducing energy waste and improving the energy conversion efficiency of the entire heat exchange system. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a side view of the present invention; Figure 3 This is a schematic diagram of the heat exchange plate of the present invention; Figure 4 This is a cross-sectional view of the heat exchange plate of the present invention.

[0026] In the diagram: 1. Lower heat exchange box; 2. Lower heat exchange cavity; 3. Heat exchange plate; 4. Thin plate; 5. Welded section; 6. First flow cavity; 7. First opening; 8. Second opening; 9. Main heat exchange box; 10. Main heat exchange cavity; 11. Heat exchange tube; 12. Upper gas manifold; 13. Return manifold; 14. Upper gas manifold; 15. Return manifold; 16. First cavity; 17. Second cavity; 18. Separating welded section; 19. Flue gas inlet; 20. Flue gas outlet; 21. Inlet of the fluid to be exchanged; 22. Outlet of the fluid to be exchanged; 23. Manifold. Detailed Implementation

[0027] The present invention will now be described through specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of the inventive concept are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0028] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used in this invention are conventional in the art and can be obtained through conventional commercial means; unless otherwise specified, the methods used in this invention are conventional methods in the art.

[0029] Example 1: Reference Figure 1 to Figure 4As shown, this invention provides a vacuum plate heat exchanger, including an upper heat exchange assembly and a lower heat exchange box 1. The lower heat exchange box 1 has a lower heat exchange cavity 2 and multiple sets of heat exchange plates 3 spaced apart within the lower heat exchange cavity 2. A flue gas channel for flue gas circulation is formed between two adjacent sets of heat exchange plates 3. The heat exchange plates 3 are welded together by two thin plates 4 arranged one behind the other through several welding parts 5. The unwelded parts of the heat exchange plates 3 are far apart from each other, forming several first flow cavities 6 that are interconnected at the bottom. The top of the heat exchange plates 3 is provided with... The first flow chamber 6 has a first opening 7 and a second opening 8 connected to the first flow chamber 6. The first flow chamber 6 contains a phase change fluid. The lower heat exchange box 1 has a flue gas inlet 19 connecting the flue gas channel and the flue gas inlet pipe, and a flue gas outlet 20 connecting the flue gas channel and the flue gas outlet pipe on both sides. The upper heat exchange assembly includes a main heat exchange box 9 with a main heat exchange chamber 10, a manifold, and a manifold box 23 with a manifold. The main heat exchange box 9, the manifold, and the manifold box 23 are arranged sequentially from top to bottom. The main heat exchange box 9 is provided with a connecting heat exchange pipe 11. The main heat exchange chamber 10 has an inlet 21 and an outlet 22 for the fluid to be exchanged, connected to an external liquid pipe. A heat exchange tube 11 is provided within the main heat exchange chamber 10, and a second flow chamber for the fluid to be exchanged is provided within the heat exchange tube 11. A manifold extends along the arrangement direction of multiple heat exchange plates 3. The manifold box 23 includes an upper gas manifold box 12 and a return gas manifold box 13. One end of the manifold pipe is welded to the main heat exchange chamber 9, and the other end is welded to the manifold box 23. It includes an upper gas manifold pipe 14 and a return gas manifold pipe 15. The upper gas manifold box... The manifold of chamber 12 is connected to the main heat exchange chamber 10 via the upper gas manifold 14. The manifold of the return manifold 13 is connected to the bottom of the main heat exchange chamber 10 via the return manifold 15. The height of the connection between the upper gas manifold 14 and the main heat exchange chamber 10 is higher than the height of the connection between the return manifold 15 and the main heat exchange chamber 10. The top of the thin plate 4 is welded to the bottom of the manifold 23 so that the first opening 7 is connected to the manifold of the upper gas manifold 12, and the second opening 8 is connected to the manifold of the return manifold 13. In operation, flue gas enters the lower heat exchange chamber 2 from the flue gas inlet 19, exchanges heat with the heat exchange plate 3 during the flow process, and is finally discharged from the flue gas outlet 20. When the equipment does not need to supply flue gas, the valves at the flue gas inlet 19 and the flue gas outlet 20 are closed simultaneously. The positions of the flue gas inlet 19 and the flue gas outlet 20 determine the flow direction of the flue gas. As shown in Figure 1, in this embodiment, the X direction is the flow direction of flue gas in the flue gas channel. The entire left side of the vacuum plate heat exchanger is the flue gas inlet, and the entire right side is the flue gas outlet. After the flue gas enters the flue gas channel of the lower heat exchange chamber 2 from the left inlet, it flows along the X direction through the area between each adjacent heat exchange plate 3, and finally exits from the right outlet.

[0030] In the aforementioned vacuum plate heat exchanger, flue gas is introduced into the lower heat exchange chamber 2, and the first flow chamber 6 of the heat exchange plate 3 is filled with liquid phase change fluid. The flue gas exchanges heat with the phase change fluid, causing the phase change fluid to change from a liquid state to a gaseous state. The gaseous phase change fluid flows through the first opening 7, the upper gas manifold box 12, and the upper gas manifold pipe 14 to the main heat exchange chamber 10, transferring heat to the heat exchange tube 11, and then transferring the temperature to the fluid to be heat exchanged in the heat exchange tube 11, achieving efficient heat exchange. After heat exchange, the temperature of the phase change fluid decreases, and it becomes liquid again. It then falls back into the first flow chamber 6 through the return manifold pipe 15, the return manifold box 13, and the second opening 8. This cycle indirectly transfers the heat of the flue gas to the fluid to be heat exchanged.

[0031] In this vacuum plate heat exchanger, the first opening 7, the upper gas manifold box 12, and the upper gas manifold pipe 14 form a dedicated airflow channel for gaseous phase change fluid to enter the main heat exchange chamber 10. The return manifold pipe 15, the return manifold box 13, and the second opening 8 form a dedicated liquid flow channel for the condensed liquid phase change fluid to fall back into the first flow chamber 6. This separation design of gas and liquid flow channels eliminates gas-liquid flow conflicts. Furthermore, combined with the height difference between the upper gas manifold pipe 14 and the return manifold pipe 15, gravity further enhances the reflux force of the liquid phase change fluid, achieving efficient circulation of the phase change material and ensuring stable and efficient heat exchange. In addition, the top of the thin plate 4 is welded to the bottom of the manifold box 23, achieving a sealed connection between the heat exchange plate 3 and the manifold box 23. This invention achieves a sealed connection between multiple first flow chambers 6 and the manifold box 23 through a single centralized welding of the heat exchange plate 3 and the main heat exchange box 9. This results in fewer welding points, lower welding quality control difficulty, higher welding quality, less leakage of heat exchange fluid, and higher heat exchange efficiency. In terms of structural design, the heat exchange tube 11, which does not require welding, is placed in the main heat exchange chamber. The fluid to be exchanged is placed inside the heat exchange tube 11. The fluid to be exchanged is not easy to leak, and the gaseous phase change fluid is not easy to enter the heat exchange tube 11. At the same time, the interval between the heat exchange plates 3 is used as the flue gas passage to reduce the leeward area, reduce the degree of ash accumulation, and ensure stable heat exchange efficiency.

[0032] The heat exchange plate 3 of this invention is manufactured in a factory by machine welding. First, the edges of two thin metal sheets are precisely welded and sealed to form a flat unit with a closed perimeter. Then, high-pressure gas is introduced into the interior through a reserved channel, causing the non-welded area in the middle to expand and deform, ultimately forming a first flow cavity 6 with a specific cavity structure. During on-site installation, only manual welding of the bottom of the heat exchange plate 3 and the manifold 23 is required to seal the heat exchange plate 3 to the main heat exchange box 9, and to achieve synchronous sealing connection of multiple first flow cavities 6 with corresponding main heat exchange cavities 10, making the connection simple and efficient.

[0033] In this invention, the core limitation of the structural design of the upper gas manifold 14 and the return manifold 15 is that there is a height difference between the two and the main heat exchange chamber 10 at the connection position. That is, the height of the connection position between the upper gas manifold 14 and the main heat exchange chamber 10 must be higher than that of the connection position between the return manifold 15 and the main heat exchange chamber 10. This ensures the gravity return force of the liquid phase change fluid and realizes efficient separation of the gas-liquid flow channel. The present invention does not impose additional limitations on the specific shape of the upper gas manifold 14, the return manifold 15 and the main heat exchange box 9.

[0034] As a preferred option, such as Figure 2 As shown, the main heat exchange box 9 is a cylinder, and the return manifold 15 is connected to the bottom of the main heat exchange box 9. When the gaseous phase change fluid releases heat and condenses into a liquid state in the main heat exchange chamber 10, the smooth arc-shaped inner wall of the cylinder can replace the additional flow guiding component, guiding the liquid phase change fluid to slide naturally along the inner wall to the central area at the bottom of the chamber and converge. The converged liquid phase change fluid can flow into the return manifold 15 quickly and smoothly under the action of gravity, improving circulation efficiency and reducing dead zones of liquid accumulation.

[0035] In a preferred embodiment of the present invention, the upper heat exchange assembly includes multiple mutually isolated main heat exchange boxes 9. Each main heat exchange box 9 is provided with multiple manifold boxes 23, and the manifold boxes 23 corresponding to different main heat exchange boxes 9 are mutually isolated. The manifold boxes 23 are connected to the corresponding main heat exchange boxes 9 through corresponding manifold pipes. Each main heat exchange cavity 10 is provided with multiple heat exchange plates 3, and the heat exchange plates 3 are connected to the corresponding manifold boxes 23. The heat exchange plates 3, the corresponding manifold boxes 23, and the main heat exchange boxes 9 form independent heat exchange units, preventing structural failures in one unit from affecting the operation of the entire equipment. At the same time, the flow channels, pipes, and heat exchange plates 3 of each unit are completely independent and have no common manifold carrier. When a unit needs maintenance, there is no need to shut down the entire system. In addition, in this scheme, the parameters of each main heat exchange box 9 can be designed independently, which provides high flexibility. From the perspective of the leakage process, if a unit leaks, the phase change fluid inside it will be discharged through the leak point. However, since the phase change fluid of each unit only circulates in its own closed loop and there is no external replenishment, the leakage will stop naturally after the fluid in that unit has finished leaking. This will not cause the phase change fluid of other units to be lost. For the entire heat exchange equipment, even if a small number of heat exchange units stop operating due to failure, the remaining normally operating heat exchange units can still ensure that the total heat exchange of the entire equipment meets the heat exchange requirements of production. The flue gas passage of the lower heat exchange box 1 is under negative pressure, making it difficult for flue gas to enter the main heat exchange chamber 10 in reverse through the leak point. At the same time, the heat exchange tube 11 itself has anti-corrosion properties. Even if a small amount of flue gas enters the faulty unit, it is not easy to damage the heat exchange tube 11, thus achieving precise control of failure risk.

[0036] In another embodiment, the main heat exchange box 9 includes multiple isolated main heat exchange chambers 10. Each main heat exchange chamber 10 is equipped with multiple heat exchange plates 3, and each heat exchange plate 3 is only connected to its corresponding main heat exchange chamber 10. That is, each main heat exchange chamber 10 is equipped with a manifold box 23, and the manifold boxes 23 corresponding to different main heat exchange boxes 9 are isolated from each other. The multiple heat exchange plates 3 and the multiple isolated main heat exchange chambers 10 form independent heat exchange units, thereby preventing structural failure of a certain unit from affecting the operation of the entire equipment. In this solution, the main heat exchange box 9 is a common carrier, the assembly process is simpler, and the manufacturing cost is lower. It is suitable for cost-sensitive scenarios with medium heat exchange scale, such as waste heat recovery of small and medium-sized industrial boilers.

[0037] In this embodiment, as Figure 1 As shown, the heat exchange plate 3 is provided with a vertically extending partition welded part 18, which divides the first flow cavity 6 inside the heat exchange plate 3 into a first cavity 16 and a second cavity 17. The bottom of the first cavity 16 and the second cavity 17 are connected but the tops are isolated. The first opening 7 is located at the top of the first cavity 16 and is connected to the first cavity 16. The second opening 8 is located at the top of the second cavity 17 and is connected to the second cavity 17. When the liquid phase change fluid falls back to the second cavity 17 through the second opening 8, it will automatically flow to the first cavity 16 along the bottom area connecting the two cavities under the action of gravity and the fluid's own flow, realizing the uniform distribution of the phase change fluid in the entire heat exchange plate 3. This avoids the problem of wasted heat exchange area or decreased heat exchange efficiency due to insufficient local fluid. Moreover, the liquid enters from the bottom to avoid conflict with the rising gas, ensuring smooth circulation.

[0038] like Figure 1 As shown, the first chamber 16 is located near the flue gas inlet 19, and the second chamber 17 is located near the flue gas outlet 20. The flue gas carries the most heat when it first enters the equipment. As it flows along the flue gas channel, it gradually releases heat, and by the time it reaches the flue gas outlet 20, its temperature has decreased. The liquid phase change fluid falling back into the second chamber 17 is kept in a relatively low-temperature flue gas environment, effectively preventing the liquid phase change fluid from heating and vaporizing during the recirculation process. This also prevents the liquid phase change fluid from reabsorbing heat and vaporizing due to contact with high-temperature flue gas during the recirculation process, thus preventing the phase change material from turning into a gaseous state again and affecting the recirculation of the liquid phase change fluid, ensuring efficient circulation of the phase change material.

[0039] Furthermore, the length of the first cavity 16 in the flue gas flow direction is greater than the length of the second cavity 17 in the flue gas flow direction. By extending the length of the first cavity 16 in the flue gas flow direction, the longer contact path allows the phase change fluid to more fully absorb the heat released by the flue gas, improving gasification efficiency and providing a more sufficient heat energy carrier for the subsequent heat exchange between the main heat exchange cavity 10 and the fluid to be exchanged. Shortening the length of the second cavity 17 avoids setting too much ineffective heat exchange area in the low-temperature region, thereby improving the energy conversion efficiency of the entire heat exchange system.

[0040] Furthermore, in this embodiment, three upper gas manifolds 14 are provided, and one return manifold 15 is provided. The top of the first cavity 16 has three first openings 7, and the top of the second cavity 17 has one second opening 8. Since gaseous phase change fluids have large intermolecular distances and high volume ratios, they have higher space requirements for the flow channel. Increasing the number of upper gas manifolds 14 can significantly widen the flow cross-section of the gaseous fluid, reduce the resistance during gas flow, and ensure that the gaseous phase change fluid enters the main heat exchange cavity 10 quickly and uniformly. Liquid phase change fluids have denser molecules and smaller volumes, so only a few return manifolds 15 are needed to meet their flow requirements. In addition, the core function of the return manifold 15 is to transport the condensed liquid fluid, rather than to participate in heat exchange. Reducing the number of return manifolds 15 can reduce the heat exchange area of ​​the liquid return section.

[0041] Furthermore, such as Figure 2 As shown, the top of the upper gas manifold 14 extends into the main heat exchange chamber 10 and protrudes from the inner wall of the main heat exchange box 9. When the gaseous phase change fluid is transported to the main heat exchange chamber 10 through the upper gas manifold 14, the gas can diffuse more fully into the internal space of the main heat exchange chamber 10, enhancing the heat exchange efficiency. In addition, the port of the upper gas manifold 14 protrudes from the inner wall and its connection position is higher than that of the return manifold 15, making it difficult for the liquid fluid to rise to the height of the port and enter the interior of the upper gas manifold 14, maintaining strict separation of the gas and liquid flow channels and ensuring the stability and smoothness of the phase change fluid circulation.

[0042] In this embodiment, the manifold of the upper gas manifold 12 corresponding to the same main heat exchanger 9 is connected to the manifold of the return manifold 13. That is, the upper gas manifold 12 and the return manifold 13 share the same manifold, which can reduce the overall number of manifolds 23 and assembly steps, significantly simplify the equipment structure, and reduce the cost of housing manufacturing and sealing components. This structure is suitable for operating conditions where the flue gas heat fluctuation is small and the phase change fluid gasification rate is relatively stable.

[0043] In other embodiments, the manifold of the upper gas manifold 12 corresponding to the same main heat exchanger 9 is isolated from the manifold of the return manifold 13. That is, the upper gas manifold 12 and the return manifold 13 use different manifolds, or a partition is set inside the same manifold 23 to isolate the upper gas manifold 12 from the return manifold 13. When the upper gas manifold and the return manifold are isolated, the upper gas manifold is only used to transport gaseous phase change fluid, and the return manifold is only used to return liquid phase change fluid. There is no fluid exchange channel between the two, ensuring that the gas and liquid two-phase fluids flow stably along their respective paths. In addition, the isolation design also facilitates independent monitoring and control of the pressure and flow rate of the gas and liquid two-phase fluids, which is suitable for scenarios with high heat exchange accuracy requirements and strict control of fluid state.

[0044] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0045] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A vacuum plate heat exchanger, characterized in that, The system includes an upper heat exchange assembly and a lower heat exchange box (1). The lower heat exchange box (1) is provided with a lower heat exchange cavity (2) and multiple sets of heat exchange plates (3) spaced apart in the lower heat exchange cavity (2). A flue gas channel for flue gas circulation is formed between two adjacent sets of heat exchange plates (3). The heat exchange plate (3) is welded by two thin plates (4) arranged one behind the other through several welding parts (5). The unwelded parts of the heat exchange plate (3) are far apart from each other to form several first flow cavities (6) that are interconnected at the bottom. The top of the heat exchange plate (3) is provided with a first opening (7) and a second opening (8) that are connected to the first flow cavities (6). A phase change fluid is provided in the first flow cavities (6). The upper heat exchange assembly includes a main heat exchange box (9) with a main heat exchange cavity (10), a manifold, and a manifold box (23) with a manifold cavity. The main heat exchange box (9), the manifold, and the manifold box (23) are arranged sequentially from top to bottom. A heat exchange tube (11) is provided in the main heat exchange cavity (10). The heat exchange tube (11) is provided with a second flow chamber for the flow of the fluid to be exchanged. The flow chamber extends along the arrangement direction of the multiple heat exchange plates (3). The flow box (23) includes an upper flow box (12) and a return flow box (13). The flow pipe includes an upper flow pipe (14) and a return flow pipe (15). The flow chamber of the upper flow box (12) is connected to the main heat exchange chamber (10) through the upper flow pipe (14). The flow chamber of the return flow box (13) is connected to the main heat exchange chamber (10) through the upper flow pipe (14). The cavity is connected to the bottom of the main heat exchange cavity (10) through the return manifold (15). The height of the connection between the upper gas manifold (14) and the main heat exchange cavity (10) is higher than the height of the connection between the return manifold (15) and the main heat exchange cavity (10). The top of the thin plate (4) is welded to the bottom of the manifold box (23) so that the first opening (7) is connected to the manifold cavity of the upper gas manifold box (12) and the second opening (8) is connected to the manifold cavity of the return manifold box (13).

2. A vacuum plate heat exchanger according to claim 1, characterized in that, The heat exchange plate (3) is provided with a vertically extending partition welding part (18). The partition welding part (18) divides the first flow cavity (6) in the heat exchange plate (3) into a first cavity (16) and a second cavity (17). The bottom of the first cavity (16) and the second cavity (17) are connected and the top is isolated. The first opening (7) is located at the top of the first cavity (16) and is connected to the first cavity (16). The second opening (8) is located at the top of the second cavity (17) and is connected to the second cavity (17).

3. A vacuum plate heat exchanger according to claim 2, characterized in that, The first cavity (16) is located on the side near the flue gas inlet (19), and the second cavity (17) is located on the side near the flue gas outlet (20).

4. A vacuum plate heat exchanger according to claim 2, characterized in that, The length of the first cavity (16) in the flue gas flow direction is greater than the length of the second cavity (17) in the flue gas flow direction.

5. A vacuum plate heat exchanger according to claim 1, characterized in that, The main heat exchange box (9) is a cylinder.

6. A vacuum plate heat exchanger according to claim 1, characterized in that, The top of the upper air manifold (14) extends into the main heat exchange chamber (10) and protrudes from the inner wall of the main heat exchange box (9).

7. A vacuum plate heat exchanger according to any one of claims 1 to 6, characterized in that, The manifold of the upper manifold (12) is connected to the manifold of the return manifold (13); or, the manifold of the upper manifold (12) is isolated from the manifold of the return manifold (13).

8. A vacuum plate heat exchanger according to any one of claims 1 to 6, characterized in that, The number of upper air manifolds (14) is greater than that of the return air manifolds (15).

9. A vacuum plate heat exchanger according to any one of claims 1 to 6, characterized in that, The main heat exchange box (9) includes multiple mutually isolated main heat exchange chambers (10), each main heat exchange chamber (10) is provided with multiple heat exchange plates (3), and each heat exchange plate (3) is only connected to the corresponding main heat exchange chamber (10).

10. A vacuum plate heat exchanger according to any one of claims 1 to 6, characterized in that, The upper heat exchange assembly includes multiple mutually isolated main heat exchange boxes (9), each main heat exchange box (9) is provided with multiple manifold boxes (23), and the manifold boxes (23) corresponding to different main heat exchange boxes (9) are mutually isolated. The manifold box (23) is connected to the corresponding main heat exchange box (9) through the corresponding manifold pipe. Each main heat exchange cavity (10) is provided with multiple heat exchange plates (3), and the heat exchange plates (3) are connected to the corresponding manifold box (23).

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