A vacuum plate heat exchanger

Abstract

The application relates to a vacuum plate heat exchanger and relates to the technical field of heat exchange equipment. The vacuum plate heat exchanger comprises an upper heat exchange box and a lower heat exchange box, the upper heat exchange box is internally provided with an upper heat exchange cavity, the lower heat exchange box is provided with a flue gas channel, the lower heat exchange box is internally provided with a heat exchange plate, the lower part of the heat exchange plate is located in the flue gas channel, and a vertical first flow cavity for containing a phase change fluid is formed in the heat exchange plate; the upper part of the heat exchange plate extends into the upper heat exchange cavity, the upper heat exchange cavity is provided with a fluid inlet and a fluid outlet for inflow and outflow of a fluid to be heat exchanged, and the first flow cavity and the upper heat exchange cavity are mutually isolated. The application can effectively solve the problems of many sealing nodes, high leakage risk, long heat transfer path and complex manufacturing process caused by the split setting of an evaporation section and a condensation section in the prior art, and the reliability and heat exchange efficiency of equipment operation are improved.

Description

Technical Field

[0001] This utility model relates to the field of heat exchange equipment technology, specifically to a vacuum plate heat exchanger. Background Technology

[0002] Vacuum plate heat exchangers are widely used in the field of flue gas waste heat recovery. Their working principle is to use liquid phase change fluid to absorb heat from flue gas in the evaporation section and then vaporize it. The gaseous phase change fluid rises to the condensation section, transfers heat to the fluid to be exchanged, and then condenses and flows back. This cycle achieves efficient heat transfer.

[0003] In existing technologies, vacuum plate heat exchangers generally adopt a split structure, meaning that the evaporation section and the condensation section are composed of different heat exchange elements. For example, a heat exchange plate is set in the lower heat exchange box as the evaporation section, and a vertical first flow cavity is formed inside the heat exchange plate to accommodate the phase change fluid; an independent heat exchange tube or heat exchange plate is set in the upper heat exchange box as the condensation section for the flow of the fluid to be heat exchanged. The upper end of the first flow cavity in the lower heat exchange plate is connected to the upper heat exchange cavity through an opening, through which the gaseous phase change fluid enters the upper heat exchange cavity and releases heat upon contact with the outer surface of the heat exchange elements in the condensation section. Although this structure can achieve basic heat transfer functions, it has the following obvious drawbacks in practical applications: First, the numerous connection points increase the risk of leakage. The lower heat exchange plate needs to be connected to the upper heat exchange chamber via openings, and these openings must be sealed by welding. When the upper and / or lower heat exchange boxes have multiple independent chambers, each chamber's corresponding lower heat exchange plate needs multiple openings to be made and sealed with the upper chamber, creating numerous welded joints. These joints are constantly exposed to high temperatures and pressure fluctuations, making them highly susceptible to becoming potential leak points. If a weld fails, outside air will enter the sealed chamber, disrupting the vacuum and causing a sharp drop in heat exchange efficiency or even equipment failure.

[0004] Second, the heat transfer path is lengthy, limiting heat exchange efficiency. The gaseous phase change fluid must flow upward from the first flow chamber of the lower heat exchange plate through the connecting opening, enter the upper heat exchange chamber, and then diffuse laterally to the outer surface of the heat exchange tube or the upper heat exchange plate for condensation. Throughout the process, the gaseous phase change fluid undergoes abrupt changes in cross-section and flow direction, resulting in certain flow resistance and pressure drop, which slows down the circulation rate. Simultaneously, the phase change fluid and the fluid to be heat-exchanged are separated by multiple interfaces, including the heat exchange plate wall, the path of the connecting opening, and the wall of the condensing element, leading to accumulated thermal resistance and affecting the overall heat exchange efficiency.

[0005] Third, the manufacturing and assembly processes are complex. The split structure requires the separate manufacturing of the lower heat exchange plate and the upper heat exchange element (tube or plate), and precise alignment and welding during final assembly. The manufacturing processes of the upper and lower elements may differ, requiring multiple sets of tooling and equipment, a wide variety of parts, and cumbersome assembly procedures, making it difficult to guarantee the efficiency and consistency of mass production.

[0006] Therefore, how to simplify the structure of vacuum plate heat exchangers, reduce sealing nodes to lower the risk of leakage, shorten the heat transfer path to improve heat exchange efficiency, and standardize manufacturing processes to reduce costs are technical problems that urgently need to be solved in this field. Utility Model Content

[0007] The purpose of this invention is to provide a vacuum plate heat exchanger to solve the problems of multiple sealing nodes, high leakage risk, long heat transfer path and complex manufacturing process caused by the separate setting of evaporation section and condensation section in the prior art.

[0008] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution: A vacuum plate heat exchanger includes an upper heat exchange box and a lower heat exchange box. The upper heat exchange box is provided with an upper heat exchange cavity, and the lower heat exchange box has a flue gas passage. A heat exchange plate is provided in the lower heat exchange box, and the lower part of the heat exchange plate is located in the flue gas passage. A vertical first flow cavity is formed inside the heat exchange plate, and the first flow cavity contains a phase change fluid. The upper part of the heat exchange plate extends into the upper heat exchange cavity, which has a fluid inlet and a fluid outlet for the fluid to be exchanged to flow in and out; the first flow cavity is isolated from the upper heat exchange cavity.

[0009] In the aforementioned vacuum plate heat exchanger, the upper part of the heat exchange plate is flat, and the upper parts of multiple heat exchange plates are parallel to each other and spaced apart. A fluid channel for the flow of the fluid to be heat exchanged is formed between the upper parts of two adjacent heat exchange plates.

[0010] In the aforementioned vacuum plate heat exchanger, the upper part of the heat exchange plate is arranged vertically or inclined so that the phase change fluid in the first flow chamber can flow back to the lower part of the heat exchange plate under the action of gravity after condensation.

[0011] In the aforementioned vacuum plate heat exchanger, the upper part of the heat exchange plate is vertically arranged, and the upper parts of multiple heat exchange plates are arranged sequentially along the horizontal direction.

[0012] In the aforementioned vacuum plate heat exchanger, fins are provided on the upper front and back surfaces of the heat exchange plate, and the fins are arranged parallel to or inclined to the flow direction of the fluid to be heat exchanged.

[0013] In the above-mentioned vacuum plate heat exchanger, there are multiple upper heat exchange chambers that are isolated from each other. The multiple upper heat exchange chambers are arranged sequentially along the flue gas flow direction, and the upper part of the heat exchange plate extends into each upper heat exchange chamber.

[0014] In the aforementioned vacuum plate heat exchanger, adjacent upper heat exchange chambers are connected by connecting pipes, allowing the fluid to be heat exchanged to flow through each upper heat exchange chamber in sequence, forming a series of heat exchange channels.

[0015] In the aforementioned vacuum plate heat exchanger, the heat exchange plate is formed by welding two thin plates together through several welding points, and the unwelded parts of the two thin plates are far apart to form a first flow cavity.

[0016] In the aforementioned vacuum plate heat exchanger, a partition is provided between the upper heat exchange box and the lower heat exchange box, the heat exchange plate passes through the partition, and the heat exchange plate and the partition are sealed together at the point of penetration.

[0017] In the aforementioned vacuum plate heat exchanger, the partition plate is provided with slots through which the heat exchange plate passes, and the heat exchange plate and the slots are sealed by welding.

[0018] Compared with the prior art, the advantages of this utility model are: The heat exchange plate directly penetrates the partition between the lower heat exchange box and the upper heat exchange chamber. The first flow chamber inside the heat exchange plate is a complete, continuous, closed cavity, with its upper end sealed off from the upper heat exchange chamber. After absorbing heat from the flue gas and vaporizing, the phase change fluid rises along the first flow chamber into the upper part of the heat exchange plate located in the upper heat exchange chamber. Here, it releases heat to the fluid to be exchanged and then condenses and flows back. The entire circulation process is completed inside the heat exchange plate, and the gaseous phase change fluid does not need to leave the heat exchange plate to enter the upper heat exchange chamber space. This structure fundamentally eliminates the necessary connecting openings in the split design, reducing the number of connection nodes between the upper and lower components to zero. The only through-sealing part is the single annular weld formed by the partition between the heat exchange plate and the upper and lower heat exchange chambers. The sealing nodes are highly concentrated, the welding operation is simple, the quality is easy to control, and the leakage risk is reduced by orders of magnitude compared to the split design. The long-term vacuum maintenance capability and reliability of the equipment are fundamentally improved.

[0019] The entire heat transfer process occurs entirely on both sides of the heat exchange plate's own wall, without requiring external chamber space or additional connecting structures. The phase change fluid rises and flows back vertically within the first flow chamber, ensuring a smooth flow path with no throttling losses; heat only needs to penetrate one layer of metal wall, minimizing thermal resistance. Simultaneously, because the first flow chamber is completely isolated from the upper heat exchange chamber, there is no possibility of direct contact or mixing between the fluid to be heat exchanged and the phase change fluid. Even if the fluid to be heat exchanged is a gaseous medium such as air, there will be no cross-contamination with the phase change fluid, ensuring the purity and safety of the system operation.

[0020] The core heat exchange element of the entire heat exchanger is only a heat exchange plate of one structure, which can be manufactured as a whole by welding two thin plates together and blowing them into shape using a standardized process. There is no need to produce and assemble the lower heat exchange plate and the upper heat exchange element separately. The types of parts are greatly reduced, the assembly process is simplified, the manufacturing cost is significantly reduced, and the consistency of product quality and the efficiency of mass production are effectively guaranteed.

[0021] Furthermore, the upper part of the heat exchange plate is flat, with multiple heat exchange plates arranged parallel to each other and spaced apart. A fluid channel for the fluid to be heated is formed between the upper parts of adjacent heat exchange plates. By designing the upper part of the heat exchange plate as flat and using a layout of multiple parallel and spaced plates, the heat exchange area is multiplied within the limited upper heat exchange cavity space. The flat plate shape makes the surface area to volume ratio of the upper part of the heat exchange plate much higher than that of a tubular structure. The fluid to be heated flows in a thin layer in the fluid channel between adjacent plates, making full contact with both sides of the plate wall for heat exchange, and significantly improving the heat exchange efficiency. At the same time, the fluid channel formed by the multiple parallel and spaced plates has a regular cross-section and uniform spacing, and the fluid to be heated is evenly distributed in the channel, avoiding the problem of short-circuiting or forming flow dead zones. The heat exchange conditions of the upper parts of each heat exchange plate are consistent, and the outlet fluid temperature is stable and uniform. In addition, this regular parallel plate layout facilitates assembly positioning and batch welding, and the plate spacing can be precisely controlled.

[0022] Furthermore, the upper part of the heat exchange plate is vertically or inclined so that the phase change fluid in the first flow chamber can flow back to the lower part of the heat exchange plate under gravity after condensation. By limiting the upper part of the heat exchange plate to a vertical or inclined non-horizontal state, a reliable gravity return path is provided for the condensed liquid phase change fluid. During operation, the gaseous phase change fluid rises along the first flow chamber to the upper part of the heat exchange plate, exchanges heat with the fluid to be heat-exchanged, and condenses into a liquid state. The liquid phase change fluid flows downward along the inner wall of the first flow chamber under gravity and flows smoothly back to the evaporation section of the heat exchange plate located in the flue gas channel of the lower heat exchange box, completing the cycle. If the upper part of the heat exchange plate is horizontally set, the condensate will accumulate in the horizontal section and cannot flow back, causing the liquid phase change fluid in the evaporation section to gradually decrease until it dries up, and the heat exchange cycle will be forced to stop. Vertical or inclined configurations fundamentally avoid this problem, ensuring that the phase change fluid continuously and stably completes the full thermodynamic cycle of evaporation, rising, condensation, and reflux within the closed first flow chamber, without the need for external power drive, thus enabling the reliable operation of the integrated heat exchanger plate architecture.

[0023] Furthermore, the upper part of the heat exchange plates is vertically arranged, with multiple heat exchange plates arranged sequentially along the horizontal direction. By uniformly setting the upper part of all heat exchange plates to be vertical and equidistant along the horizontal direction, the upper parts of each heat exchange plate are within the same vertical height range. The outer surface of the upper part of each heat exchange plate can fully contact the fluid to be heat exchanged from bottom to top. The temperature and flow rate of the fluid to be heat exchanged are basically the same for each plate, fundamentally avoiding the problem of uneven heat exchange caused by different plate angles or irregular arrangements. At the same time, the vertical arrangement ensures that the rising direction of the gaseous phase change fluid in the first flow chamber and the return direction of the condensed liquid phase change fluid are both parallel to the direction of gravity. The flow paths of the gaseous and liquid fluids are the smoothest, the flow resistance is minimized, and the driving force of gravity return is maximized. The vertical fluid channels formed by the sequential arrangement along the horizontal direction are consistent with the flow direction of the fluid to be heat exchanged. The fluid to be heat exchanged flows uniformly over the surface of each heat exchange plate in the channel, without lateral flow around or local eddies. The flow resistance is small, the heat transfer coefficient is uniformly distributed along the height of the plate, and the heat transfer performance of each heat exchange plate is highly consistent.

[0024] Furthermore, the upper front and back surfaces of the heat exchange plate are provided with fins, which are arranged parallel to or inclined to the flow direction of the fluid to be heat exchanged. By adding fins to the upper front and back surfaces of the heat exchange plate, the heat exchange area of ​​the condensation section is significantly expanded, and the heat that can be transferred per unit plate area is significantly increased, compensating for the relatively limited heat exchange area of ​​the flat plate surface. The direction of the fins is parallel or inclined to the flow direction of the fluid to be heat exchanged, which conforms to the natural flow path of the fluid. The fluid flows smoothly along the channels between the fins, avoiding the head-on obstruction and vortex separation phenomena that occur when the fins are perpendicular to the flow direction. This enhances heat exchange while keeping the flow resistance at a low level. Among them, the parallel fins are completely consistent with the fluid flow direction, and the fluid forms a stable laminar or transitional flow between the fins, with minimal flow resistance, which is suitable for operating conditions sensitive to pressure drop. The inclined fins guide the fluid through while generating moderate lateral disturbance to the fluid, reducing the thickness of the flow boundary layer near the surface of the heat exchange plate, increasing the convective heat transfer coefficient, and further enhancing the heat exchange effect.

[0025] Furthermore, the upper heat exchange chamber is provided in multiple isolated chambers, arranged sequentially along the flue gas flow direction, with the upper part of a heat exchange plate extending from each chamber. By dividing the upper heat exchange chamber into multiple independent chambers arranged sequentially along the flue gas flow direction and isolated from each other, modular and zoned management of the heat exchange process is achieved. Utilizing the natural law that the temperature of the flue gas gradually decreases during flow, the upper part of the heat exchange plate in each upper heat exchange chamber corresponds to the flue gas heat at different temperature ranges, forming a graded condensation region that matches the flue gas temperature gradient. The upper heat exchange chamber that the flue gas first contacts has the highest temperature, and the condensation temperature and pressure of the phase change fluid in the upper part of the heat exchange plate within it are also the highest, enabling preferential transfer of heat from the high-temperature flue gas to the fluid to be heat exchanged; as the flue gas flows downstream, the temperature decreases step by step, and the heat exchange intensity in subsequent upper heat exchange chambers decreases accordingly. This tiered layout allows the fluid to gradually heat up as it flows through each stage of the upper heat exchange chambers, avoiding the localized thermal stress shocks that can occur with large temperature differences in a single-chamber centralized heat exchange. This results in a more uniform and stable outlet temperature. Because the upper heat exchange chambers are isolated from each other, when a leak or blockage occurs on the upper part of the heat exchange plate in a particular chamber, the circulation of the corresponding phase change fluid in the faulty chamber is interrupted only within the first flow chamber of that faulty heat exchange plate, without affecting the heat exchange plates in adjacent chambers. The remaining heat exchange units can still operate normally, achieving precise fault isolation and degraded fault-tolerant operation of the equipment, ensuring the equipment's continuous operation under partial fault conditions.

[0026] Furthermore, adjacent upper heat exchange chambers are connected by connecting pipes, allowing the fluid to be heat-exchanged to flow through each upper heat exchange chamber sequentially, forming a series-connected heat exchange channel. By connecting multiple independent upper heat exchange chambers in series into a complete continuous channel, the fluid to be heat-exchanged passes through each heat exchange chamber sequentially during a single flow, achieving multi-stage continuous heat exchange. The fluid to be heat-exchanged absorbs heat released from the upper part of the heat exchange plates in each chamber step by step within the series-connected channel, significantly extending the heat exchange path and allowing the outlet temperature to reach a higher target value. This avoids the problem of insufficient outlet temperature caused by limited heat exchange area or temperature rise space in single-chamber heat exchange. In addition, this external series-connected layout allows the heat exchange units of each chamber to be pre-assembled in the factory, and on-site assembly can be completed simply by connecting the pipes. This facilitates flexible adjustment of the number of series stages according to actual heat demand and operating conditions, improving the modular expansion capability and engineering adaptability of the equipment.

[0027] Furthermore, the heat exchange plate is formed by welding two thin plates together through several weld points. The unwelded portions of the two plates are far apart, forming a first flow cavity. The first flow cavity is formed by welding and blowing two thin plates, eliminating the need for complex processes such as machining internal cavities or brazing multi-layer plates during the manufacturing process. After the two thin plates are welded and sealed around their perimeter, high-pressure gas is introduced into the interior to cause plastic deformation of the unwelded areas, causing them to move away from each other and naturally forming the required vertical flow channel space. This manufacturing method allows for precise control of the cross-sectional shape, cavity width, and flow channel orientation of the first flow cavity through weld point layout and blowing parameters. The inner wall of the flow channel is smooth and burr-free, resulting in low flow resistance of the phase change fluid and low condensate backflow resistance within the cavity. The entire heat exchange plate, from the lower evaporation section to the upper condensation section, can be integrally formed in the same process, eliminating the need for segmented manufacturing and welding connections. The plate body has no splicing welds, resulting in high overall structural strength and good sealing reliability.

[0028] Furthermore, a partition is provided between the upper and lower heat exchange boxes, with the heat exchange plate penetrating through the partition. The heat exchange plate and the partition are sealed at the penetration point. The partition physically separates the flue gas passages of the upper and lower heat exchange boxes, and the seal is only applied at the penetration point of the heat exchange plate, achieving reliable isolation between the two working areas. The presence of the partition ensures complete independence between the flue gas side and the side of the fluid to be exchanged. Flue gas cannot enter the upper heat exchange box and contaminate the fluid to be exchanged, and the fluid to be exchanged will not leak into the lower heat exchange box, affecting flue gas flow or corroding the lower part of the heat exchange plate. More importantly, the penetration point between the heat exchange plate and the partition is the only location where the entire heat exchange plate needs to be sealed to the external structure. A welded seal is only required at the single annular perimeter penetrating the partition, simultaneously achieving the triple functions of mechanical fixation of the heat exchange plate, environmental isolation between the upper and lower chambers, and integrity protection of the phase change fluid sealed chamber. This structure concentrates all the sealing requirements of the equipment on the fewest and simplest through welds. The sealing nodes are highly concentrated, the welding operation space is ample, and the weld quality is easy to detect and ensure. From the design level, it minimizes the risk of sealing failure and provides structural protection for the long-term reliable operation of the integrated heat exchange plate.

[0029] Furthermore, the partition plate is provided with slots for the heat exchange plate to pass through, and the heat exchange plate is sealed to the slots by welding. The combination of the slots and the weld seal provides a simple and reliable assembly and sealing method for the heat exchange plate to pass through the partition plate. The shape of the slots on the partition plate matches the cross-sectional profile of the heat exchange plate, allowing the heat exchange plate to pass directly through the slots from top to bottom or bottom to top for positioning. Assembly is simple, positioning accuracy is high, and no additional positioning fixtures or centering adjustment procedures are required. The slots form a continuous closed enclosure around the heat exchange plate. During welding, only one continuous circumferential weld is needed along the intersection of the slot and the heat exchange plate to seal the penetration point. The weld path is a single closed loop, without interruption or intersection, with a regular welding trajectory, suitable for completion in one go using automated welding equipment, resulting in stable and reliable weld quality. Meanwhile, the welded seal achieves a dual function: first, it mechanically fixes the heat exchange plate to the partition plate to withstand the stress generated by thermal expansion and contraction and fluid pressure during equipment operation; second, it completely isolates the flue gas passage of the lower heat exchange box from the upper heat exchange chamber to prevent flue gas from entering the upper heat exchange chamber. Attached Figure Description

[0030] Figure 1 This is a front view of a structure of a vacuum plate heat exchanger according to this utility model; Figure 2 This is a front view of another structure of a vacuum plate heat exchanger according to this utility model; Figure 3 This is a left view of a vacuum plate heat exchanger according to the present invention; Figure 4 This is a left view of the heat exchange plate in this utility model when the upper part is inclined. Figure 5 This is a front view of the heat exchange plate in this utility model; Figure 6 This is a cross-sectional view of the finned heat exchange plate of this utility model.

[0031] The attached figures are labeled as follows: 10. Upper heat exchanger box; 11. Upper heat exchange chamber; 12. Fluid inlet; 13. Fluid outlet; 14. Fluid channel; 15. Connecting pipe; 20. Lower heat exchanger box; 21. Flue gas channel; 30. Heat exchange plate; 31. First flow chamber; 32. Fin; 33. Thin plate; 34. Welded part; 40. Baffle. Detailed Implementation

[0032] A vacuum plate heat exchanger includes an upper heat exchange box 10 and a lower heat exchange box 20. The upper heat exchange box 10 is provided with an upper heat exchange cavity 11. The lower heat exchange box 20 has a flue gas passage 21 and a heat exchange plate 30 is provided inside the lower heat exchange box 20. The lower part of the heat exchange plate 30 is located in the flue gas passage 21. A vertical first flow cavity 31 is formed inside the heat exchange plate 30, and the first flow cavity 31 contains a phase change fluid. The upper part of the heat exchange plate 30 extends into the upper heat exchange cavity 11, which has a fluid inlet 12 and a fluid outlet 13 for the fluid to be exchanged to flow in and out; the first flow cavity 31 is isolated from the upper heat exchange cavity 11.

[0033] The heat exchange plate 30 directly penetrates the partition 40 between the lower heat exchange box 20 and the upper heat exchange chamber 11. The first flow cavity 31 inside the heat exchange plate 30 is a complete, continuous, and closed cavity, with its upper end being a closed end, completely isolated from the upper heat exchange chamber 11. After absorbing heat from the flue gas and vaporizing, the phase change fluid rises along the first flow cavity 31 and enters the upper part of the heat exchange plate 30 located in the upper heat exchange chamber 11. Here, it releases heat to the fluid to be heat exchanged and then condenses and flows back. The entire circulation process is completed inside the heat exchange plate 30, and the gaseous phase change fluid does not need to leave the heat exchange plate 30 to enter the space of the upper heat exchange chamber 11. This structure fundamentally eliminates the necessary connecting openings in the split design, reducing the number of connection nodes between the upper and lower components to zero. The only through-sealing part is the single annular weld formed by the heat exchange plate 30 and the partition 40 between the upper and lower heat exchange chambers. The sealing nodes are highly concentrated, the welding operation is simple, the quality is easy to control, and the leakage risk is reduced by orders of magnitude compared to the split design. The long-term vacuum maintenance capability and reliability of the equipment are fundamentally improved.

[0034] The entire heat transfer process occurs entirely on both sides of the heat exchange plate 30's own wall, without requiring external chamber space or additional connecting structures. The phase change fluid rises and flows back vertically within the first flow chamber 31, ensuring a smooth flow path with no throttling losses; heat only needs to penetrate one layer of metal wall, minimizing thermal resistance. Simultaneously, since the first flow chamber 31 is completely isolated from the upper heat exchange chamber 11, there is no possibility of direct contact or mixing between the fluid to be heat exchanged and the phase change fluid. Even if the fluid to be heat exchanged is a gaseous medium such as air, there will be no cross-contamination with the phase change fluid, ensuring the purity and safety of the system operation.

[0035] The core heat exchange element of the entire heat exchanger is only a heat exchange plate 30 of one structure, which can be manufactured as a whole by welding two thin plates 33 together and blowing them into shape using a standardized process. There is no need to produce and assemble the lower heat exchange plate 30 and the upper heat exchange element separately. The types of parts are greatly reduced, the assembly process is simplified, the manufacturing cost is significantly reduced, and the consistency of product quality and the efficiency of mass production are effectively guaranteed.

[0036] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0037] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0040] Vacuum plate heat exchangers are widely used in flue gas waste heat recovery. Their working principle involves a liquid phase change fluid absorbing heat from the flue gas in the evaporation section and then vaporizing. The gaseous phase change fluid rises to the condensation section, transferring heat to the fluid to be exchanged before condensing and flowing back, thus achieving efficient heat transfer in a cyclical manner. In existing technologies, vacuum plate heat exchangers generally adopt a split structure, where the evaporation and condensation sections are composed of different heat exchange elements. For example, a heat exchange plate 30 is installed in the lower heat exchange box 20 as the evaporation section, and an independent heat exchange tube or heat exchange plate 30 is installed in the upper heat exchange box 10 as the condensation section. The upper end of the flow cavity in the lower heat exchange plate 30 is connected to the upper heat exchange cavity 11 through an opening. While this structure can achieve basic heat transfer, it suffers from problems in practical applications, such as a high risk of leakage due to numerous connection points, limited heat exchange efficiency due to a long heat transfer path, and complex manufacturing and assembly processes. When the upper heat exchanger 10 and / or the lower heat exchanger 20 have multiple independent chambers, the lower heat exchanger plate 30 corresponding to each chamber needs to have multiple openings made and sealed with the upper chamber, forming a large number of welding joints. These joints are under long-term high temperature and pressure fluctuation conditions, which can easily become potential leakage points. At the same time, the gaseous phase change fluid needs to undergo abrupt changes in cross-section and flow direction, resulting in certain flow resistance and pressure drop. Moreover, there are multiple interfaces between the phase change fluid and the fluid to be heat exchanged, leading to the accumulation of thermal resistance. In addition, the split structure requires the separate manufacturing of the lower heat exchanger plate 30 and the upper heat exchange element, and precise alignment and welding during final assembly. This results in a large number of parts and a complicated assembly process.

[0041] To address the aforementioned issues, this application provides a vacuum plate heat exchanger with an integrated structure. By directly penetrating the partition 40 between the upper and lower housings through the heat exchange plate 30, the first flow cavity 31 inside the heat exchange plate 30 becomes a complete, continuous, and closed cavity, with its upper end being a closed end that is completely isolated from the upper heat exchange cavity 11. This fundamentally eliminates the necessary connecting openings in the split-type design, highly concentrates the sealing nodes, simplifies the manufacturing process, and improves heat exchange efficiency.

[0042] See Figures 1 to 6 This application provides a vacuum plate heat exchanger, including an upper heat exchange box 10 and a lower heat exchange box 20. The upper heat exchange box 10 is provided with an upper heat exchange cavity 11, and the lower heat exchange box 20 has a flue gas passage 21. The lower heat exchange box 20 is provided with a heat exchange plate 30, the lower part of which is located in the flue gas passage 21. A vertical first flow cavity 31 is formed inside the heat exchange plate 30, and the first flow cavity 31 contains a phase change fluid. The upper part of the heat exchange plate 30 extends into the upper heat exchange cavity 11. The upper heat exchange cavity 11 has a fluid inlet 12 and a fluid outlet 13 for the fluid to be heat exchanged to flow in and out. The first flow cavity 31 is isolated from the upper heat exchange cavity 11.

[0043] The upper heat exchanger 10 and lower heat exchanger 20 are container assemblies used to contain different media and form the main outer shell of the heat exchanger. The upper heat exchanger 10 is mainly used to contain the fluid to be heat exchanged and provide heat exchange space, while the lower heat exchanger 20 is mainly used to guide the high-temperature flue gas flow to provide a heat source. The two can be combined together by means of flange connection, welding, or connection through intermediate partition 40 to form a closed integral structure. The materials of the upper heat exchanger 10 and lower heat exchanger 20 can be selected according to actual working conditions, such as carbon steel, stainless steel, or corrosion-resistant alloys. The upper heat exchanger 10 and lower heat exchanger 20 together constitute the external boundary of the heat exchanger, isolating the side of the fluid to be heat exchanged and the flue gas side respectively, providing a stable working environment for the internal heat exchange components.

[0044] The upper heat exchange chamber 11 is a spatial region located inside the upper heat exchange box 10, providing a space for the fluid to be heat exchanged to circulate and exchange heat. The shape and volume of this space can be set according to heat exchange requirements, for example, it can be cuboid, cylindrical, or other irregular shapes. The upper heat exchange chamber 11 is used to accommodate the upper part of the heat exchange plate 30 and to allow the fluid to be heat exchanged to surround or flow through the upper surface of the heat exchange plate 30 for heat exchange. The upper heat exchange chamber 11 is spatially separated from the flue gas passage 21 of the lower heat exchange box 20, and the two are physically isolated by a specific structure (such as a partition 40) to prevent the flue gas from mixing with the fluid to be heat exchanged.

[0045] The flue gas passage 21 is a flow channel located within the lower heat exchanger 20 for the flow of high-temperature flue gas. The cross-sectional shape, length, and orientation of the flue gas passage 21 can be designed according to the requirements of flue gas velocity and heat exchange area; for example, it can be a rectangular channel, a circular pipe, or an irregularly shaped flow channel. The flue gas passage 21 guides the high-temperature flue gas from equipment such as boilers and industrial furnaces through the lower part of the heat exchange plate 30, transferring the heat energy in the flue gas to the heat exchange plate 30. The flue gas passage 21 and the upper heat exchange chamber 11 are located at the lower and upper parts of the heat exchanger, respectively, achieving spatial separation between the heat source side and the cold source side.

[0046] The heat exchange plate 30 is the core heat exchange component of this application, serving as both an evaporation section and a condensation section. The heat exchange plate 30 can be a single-piece plate structure, extending its lower part into the flue gas passage 21 and its upper part into the upper heat exchange chamber 11. The heat exchange plate 30 is typically made of a metal with good thermal conductivity, such as stainless steel, copper alloy, or aluminum alloy; special alloys can also be selected based on corrosion resistance requirements. The heat exchange plate 30 connects the upper and lower working areas and acts as a closed carrier for the phase change fluid and a medium for heat transfer. Through the integrated design of the heat exchange plate 30, the connection interface between the evaporation and condensation sections in traditional structures is eliminated, achieving vertical heat transfer within a single component.

[0047] The first flow cavity 31 is a closed cavity formed inside the heat exchange plate 30 to accommodate the phase change fluid and facilitate phase change circulation. The first flow cavity 31 is typically vertical to allow for natural circulation of the phase change fluid under gravity. The cross-sectional shape of the first flow cavity 31 can be flat, circular, elliptical, or polygonal, depending on the requirements for heat exchange efficiency and pressure resistance. The first flow cavity 31 provides a sealed evaporation-condensation circulation space for the phase change fluid. The first flow cavity 31 extends through the lower and upper parts of the heat exchange plate 30, but its internal space is completely isolated from the external upper heat exchange cavity 11. This means that the phase change fluid is always confined within the first flow cavity 31, preventing leakage into the upper heat exchange cavity 11 and direct contact with the fluid to be exchanged.

[0048] A phase change fluid (PCF) is a working medium that transfers heat by undergoing a phase change (liquid-gas-liquid) within the first flow chamber 31. The type of PCF can be selected based on the operating temperature range; for example, it can be water, ammonia, methanol, acetone, or mixtures thereof. The PCF's function within the first flow chamber 31 is as follows: after absorbing heat from the flue gas at the bottom, it vaporizes into a gaseous state and rises along the first flow chamber 31 to the top; after releasing heat to the fluid to be exchanged at the top, it condenses into a liquid state and flows back to the bottom under gravity. This method of heat transfer using latent heat gives the heat exchange plate 30 an extremely high equivalent thermal conductivity.

[0049] The physical structure of the heat exchange plate 30 spans the boundary between the lower heat exchange chamber 20 and the upper heat exchange chamber 10. The upper portion of the heat exchange plate 30 is completely submerged in or located within the space of the upper heat exchange chamber 11, serving as a condensation section. The length, width, and depth of this portion can be adjusted according to the size of the upper heat exchange chamber 11 and the required heat exchange area. This extended arrangement allows the phase change fluid to enter the condensation region without leaving the heat exchange plate 30 during its ascent, shortening the heat transfer path.

[0050] Fluid inlet 12 and fluid outlet 13 are interface components located on the wall of the upper heat exchange cavity 11 and connected to external pipelines, respectively. Fluid inlet 12 is used to introduce the low-temperature fluid to be exchanged into the upper heat exchange cavity 11, and fluid outlet 13 is used to discharge the heated fluid to be exchanged. The positions of fluid inlet 12 and fluid outlet 13 can be arranged on the same side, diagonally, or opposite sides to optimize the fluid distribution within the upper heat exchange cavity 11. Fluid inlet 12 and fluid outlet 13, in conjunction with the upper heat exchange cavity 11, form an inlet and outlet loop for the fluid to be exchanged, ensuring that the fluid to be exchanged can continuously flow across the upper surface of the heat exchange plate 30 for heat exchange.

[0051] The first flow chamber 31 and the upper heat exchange chamber 11 are mutually isolated. This isolation means that the inner wall of the first flow chamber 31 forms a completely closed boundary, with no openings, holes, or gaps connecting it to the upper heat exchange chamber 11 at any point. In other words, the phase change fluid is strictly confined inside the first flow chamber 31 and cannot enter the upper heat exchange chamber 11; similarly, the fluid to be exchanged in the upper heat exchange chamber 11 cannot enter the first flow chamber 31. This isolation can be achieved through sealing welding at the top of the heat exchange plate 30, integral blow molding, or other sealing processes. This directly eliminates the connection ports and sealing welds that must be provided in traditional split structures, minimizing the number of potential leakage points, ensuring the long-term stability of the system's vacuum level, and preventing cross-contamination between the two fluids.

[0052] The core innovation of this solution lies in the construction of an integrated vacuum plate heat exchanger structure. By designing the heat exchange plate 30 as a continuous component running through the upper and lower housings, and forming a closed first flow cavity 31 within it, seamless integration of the evaporation and condensation sections is achieved. This structure eliminates the open interface connecting the evaporation and condensation sections in traditional designs, completely confining the circulation process of the phase change fluid within the heat exchange plate 30, thereby solving the leakage risks caused by multi-node sealing at the structural source.

[0053] High-temperature flue gas flows through the flue gas channel 21 of the lower heat exchanger 20, washing over the lower surface of the heat exchange plate 30. Heat is transferred through the plate wall to the liquid phase change fluid in the first flow chamber 31, causing it to absorb heat and vaporize. The generated gaseous phase change fluid flows upward in the first flow chamber 31, reaching the upper part of the heat exchange plate 30 located in the upper heat exchange chamber 11. At this time, the low-temperature fluid to be heat exchanged enters the upper heat exchange chamber 11 from the fluid inlet 12 and flows over the upper surface of the heat exchange plate 30. The gaseous phase change fluid transfers heat to the fluid to be heat exchanged through the plate wall and cools and condenses into a liquid state. Under the action of gravity, the liquid phase change fluid flows downward along the inner wall of the first flow chamber 31 back to the lower part of the heat exchange plate 30, absorbs heat again, and vaporizes, thus completing the cycle. After absorbing heat and heating up, the fluid to be heat exchanged flows out from the fluid outlet 13. Throughout the entire process, the phase change fluid remains closed within the first flow chamber 31 and does not exchange any substances with the upper heat exchange chamber 11.

[0054] Assume this vacuum plate heat exchanger is used in an industrial boiler flue gas waste heat recovery system. The lower heat exchange box 20 is connected to the boiler exhaust port, and high-temperature flue gas (approximately 200℃-300℃) enters the flue gas passage 21. The heat exchange plate 30 is formed by welding and blowing two thin stainless steel plates 33 around their perimeters, creating a vertical first flow cavity 31 inside. After evacuation, a suitable amount of water is injected into the cavity as a phase change fluid. The lower part of the heat exchange plate 30 is immersed in the flue gas passage 21, and the upper part extends through the partition 40 into the upper heat exchange cavity 11 of the upper heat exchange box 10, with the top closed. The fluid inlet 12 of the upper heat exchange cavity 11 is connected to a cold air inlet pipe, and the fluid outlet 13 is connected to a hot air outlet pipe.

[0055] During operation, flue gas flows horizontally across the lower part of the heat exchange plate 30. Water absorbs heat and boils in the lower part of the first flow chamber 31, generating steam. The steam rises along the chamber to the upper part of the upper heat exchange chamber 11. Cold air enters the upper heat exchange chamber 11 and flows over the upper surface of the parallel heat exchange plates 30. The steam condenses into water on the cold wall inside the plates, and the released latent heat heats the cold air outside the plates through the plate walls. The condensate flows back down the inner wall of the plates and evaporates again. The heated air flows out from the fluid outlet 13 for user use. Because the first flow chamber 31 is completely isolated from the upper heat exchange chamber 11, even if high-pressure air is introduced into the upper heat exchange chamber 11, it will not seep into the first flow chamber 31 and disrupt the vacuum.

[0056] Through the above technical solution, by adopting a structure in which the upper part of the heat exchange plate 30 extends into the upper heat exchange cavity 11 and the first flow cavity 31 is isolated from the upper heat exchange cavity 11, the connecting opening between the evaporation section and the corresponding sealing welding node in the traditional split structure is eliminated. Therefore, the leakage risk points are significantly reduced, and the vacuum maintenance capability and reliability of the equipment during long-term operation are improved. Since the entire circulation process of the phase change fluid is completed in the closed first flow cavity 31, heat only needs to penetrate one layer of plate wall to be transferred between the phase change fluid and the fluid to be heat exchanged, shortening the heat transfer path, reducing thermal resistance, and thus improving heat exchange efficiency. Since the heat exchange plate 30 can be manufactured by an integrated process of welding and blowing two thin plates 33, there is no need to produce and assemble the upper and lower heat exchange elements separately, which simplifies the manufacturing and assembly process, reduces production costs, and improves product consistency.

[0057] Furthermore, the upper part of the heat exchange plate 30 is flat, and the upper parts of multiple heat exchange plates 30 are parallel to each other and spaced apart. A fluid channel 14 for the flow of the fluid to be heat exchanged is formed between the upper parts of two adjacent heat exchange plates 30.

[0058] The term "flat" refers to the fact that the thickness of the upper part of the heat exchange plate 30 in the direction perpendicular to its surface is much smaller than its width and height, giving it an overall thin plate shape 33. This flat structure allows the upper part of the heat exchange plate 30 to have a large surface area to volume ratio, providing a larger heat exchange area within the limited space of the upper heat exchange cavity 11. The upper part of this flat heat exchange plate 30 can be formed by welding and blowing two thin plates 33, and its internal first flow cavity 31 also adopts a flat and extended shape to accommodate the phase change fluid and achieve efficient heat exchange. The flat design not only increases the contact area with the fluid to be heat exchanged but also makes the heat transfer path shorter and the thermal resistance lower.

[0059] Multiple heat exchange plates 30 are arranged sequentially at predetermined intervals within the upper heat exchange cavity 11, with the surfaces of each heat exchange plate 30 remaining parallel to each other. This arrangement ensures that the upper part of each heat exchange plate 30 is uniformly exposed to the fluid to be heat exchanged, avoiding heat exchange dead zones caused by irregular angles or overlapping positions. Through parallel spacing, the flow field distribution among the heat exchange plates 30 tends to be consistent, ensuring that each heat exchange plate 30 can perform the same heat exchange efficiency.

[0060] The fluid channel 14 is a spatial region formed by the gap between the upper parts of two adjacent heat exchange plates 30, through which the fluid to be heat-exchanged flows. Because the upper parts of the heat exchange plates 30 are flat and arranged in parallel intervals, the fluid channel 14 has a regular cross-sectional shape and a uniform channel width. When the fluid to be heat-exchanged flows through this fluid channel 14, it is forced to flow in a thin layer tightly against the surface of the heat exchange plate 30, thereby greatly enhancing the convective heat transfer effect between the fluid and the plate wall. The width of the fluid channel 14 can be adjusted according to actual operating conditions, for example, it can be 5mm, 10mm, or 20mm, as long as it ensures smooth fluid flow without generating excessive flow resistance. This fluid channel 14 is connected to the fluid inlet 12 and fluid outlet 13 in the upper heat exchange cavity 11, forming a complete flow path for the fluid to be heat-exchanged within the upper heat exchange cavity 11.

[0061] Specifically, the flat heat exchange plates 30 work in conjunction with the parallel, spaced-apart arrangement on their upper surfaces. The fluid to be heated enters the upper heat exchange chamber 11 through the fluid inlet 12 and is guided into multiple parallel fluid channels 14 formed by the upper surfaces of the heat exchange plates 30. During its flow through the fluid channels 14, the fluid undergoes thorough heat exchange with the surfaces of the heat exchange plates 30, absorbing the heat released by the condensation of the phase-change fluid in the first flow chamber 31. Due to the regularity of the fluid channels 14, the flow velocity and flow rate are uniformly distributed within each channel, avoiding local short-circuiting or dead zones, ensuring that all heat exchange plates 30 can efficiently participate in the heat exchange process. Simultaneously, the flat structure maximizes the heat exchange area per unit volume, further improving heat exchange efficiency.

[0062] While ensuring efficient heat exchange, the heat exchange area per unit space is further increased, and the flow uniformity of the fluid to be heat exchanged is optimized. The use of multiple flat, parallelly spaced heat exchange plates 30 significantly increases the effective heat exchange area, allowing the fluid to fully contact the heat exchange surface in a thin layer, thereby greatly improving the overall heat exchange efficiency. The formation of fluid channels 14 with regular cross-sections and consistent spacing ensures uniform distribution of the fluid within each channel, effectively avoiding short-circuiting or the formation of flow dead zones, resulting in a more stable and uniform outlet fluid temperature. Furthermore, this regular parallel plate layout facilitates assembly positioning and batch welding, improving product manufacturing precision and process consistency.

[0063] Furthermore, such as Figure 3 , Figure 4 As shown, the upper part of the heat exchange plate 30 is arranged vertically or inclined so that the phase change fluid in the first flow cavity 31 can flow back to the lower part of the heat exchange plate 30 under the action of gravity after condensation.

[0064] Vertical orientation means that the upper extension direction of the heat exchange plate 30 is perpendicular to the horizontal plane, that is, the axial direction of the heat exchange plate 30 is parallel to the direction of gravity. Inclined orientation means that the upper extension direction of the heat exchange plate 30 forms an angle greater than 0 degrees and less than 90 degrees with the horizontal plane. This angle can be set according to the actual installation space, the layout of the flue gas passage 21, and the structural dimensions of the upper heat exchange box 10, for example, it can be 30 degrees, 45 degrees, 60 degrees, etc. This orientation of the heat exchange plate 30 constitutes the key driving force source for the circulation of the phase change fluid within the closed first flow cavity 31. Under the premise that the first flow chamber 31 and the upper heat exchange chamber 11 are isolated from each other, the gaseous phase change fluid rises to the upper part of the heat exchange plate 30, releases heat, and condenses into liquid. If the upper part of the heat exchange plate 30 is in a horizontal state, the condensate will accumulate at the top due to the lack of gravity component and will not be able to return to the lower evaporation section, resulting in the interruption of circulation. However, by adopting a vertical or inclined setting, the condensed liquid phase change fluid obtains a component force to move downward along the inner wall of the first flow chamber 31 under the action of gravity, so that it can smoothly flow back to the lower part of the heat exchange plate 30 located in the flue gas channel 21, reabsorb the heat of the flue gas and vaporize, and complete the self-driven thermodynamic cycle.

[0065] Since the upper part of the heat exchange plate 30 is set vertically or inclined, gravity is used as the only driving force for the return flow, which fundamentally solves the problem of condensate accumulation leading to the drying of the evaporation section and circulation failure when arranged horizontally. Furthermore, because of the non-horizontal orientation, the gas-liquid two-phase flow path in the first flow chamber 31 is smooth and the flow resistance is extremely small. The phase change fluid can be continuously circulated in the closed chamber without the need for an external power device, thereby ensuring the long-term stable operation and heat exchange efficiency of the vacuum plate heat exchanger under various operating conditions.

[0066] Ideally, the upper part of the heat exchange plate 30 is vertically arranged, and the upper parts of multiple heat exchange plates 30 are arranged sequentially along the horizontal direction.

[0067] The height direction of the upper part of the heat exchange plate 30 is basically parallel to or coincides with the direction of gravity. After the gaseous phase change fluid in the first flow chamber 31 is condensed and transformed into liquid at the upper part of the heat exchange plate 30, the liquid phase change fluid can flow smoothly back along the vertical inner wall under the action of gravity to the lower part of the heat exchange plate 30 located in the flue gas channel 21, avoiding liquid accumulation caused by the bend of the flow channel or the excessive length of the horizontal section. Due to the vertical setting, no external pumping equipment is required, thereby reducing system energy consumption and improving operational reliability. The specific angle of the vertical setting can be set according to the actual installation space and fluid dynamics requirements. For example, it can be strictly perpendicular to the horizontal plane, or it can have a slight deflection relative to the vertical direction, as long as it can ensure that the condensate effectively flows back under the action of the gravity component.

[0068] The multiple heat exchange plates 30 are arranged horizontally in the upper part, meaning that multiple flat heat exchange plates 30 are arranged side by side along the horizontal axis at a certain interval within the upper heat exchange cavity 11. This arrangement ensures that the upper part of each heat exchange plate 30 is within the same or similar vertical height range, and regular fluid channels 14 are formed between adjacent heat exchange plates 30. In this layout, after the fluid to be heat-exchanged enters from the fluid inlet 12, it can flow evenly through each fluid channel 14 formed by adjacent heat exchange plates 30, making the contact area and heat exchange conditions between the outer surface of each heat exchange plate 30 and the fluid to be heat-exchanged tend to be consistent. This arrangement, combined with the vertical setting feature, eliminates fluid short-circuiting or local dead zones caused by uneven plate heights or angles, ensuring that all heat exchange plates 30 operate under optimal conditions.

[0069] Through the above technical solution, the upper part of the heat exchange plates 30 is uniformly set vertically and arranged sequentially along the horizontal direction. Because the vertical setting makes the condensate return path consistent with the direction of gravity, the horizontal section with the greatest flow resistance is eliminated, thus ensuring the continuity and stability of the phase change fluid circulation. Furthermore, because the multiple heat exchange plates 30 are arranged sequentially along the horizontal direction to form a regular parallel flow channel, the distribution of the fluid to be exchanged between the plates is uniform and without dead corners. Therefore, the heat load of each heat exchange unit is consistent, avoiding the problem of local overheating or insufficient heat exchange, thereby improving the overall heat exchange efficiency and the reliability of equipment operation.

[0070] To increase the contact area between the upper part of the heat exchange plate 30 and the fluid to be heat exchanged, such as Figure 6 As shown, the upper front and back surfaces of the heat exchange plate 30 are provided with fins 32, which are arranged parallel to or inclined to the flow direction of the fluid to be heat exchanged.

[0071] The fins 32 are extended heat dissipation structures disposed on the outer surface of the upper condensation section of the heat exchange plate 30. Their function is to significantly increase the contact area between the heat exchange plate 30 and the fluid to be heat exchanged in the upper heat exchange cavity 11. The fins 32 can be integrally formed on the surface of the heat exchange plate 30, or they can be fixed to both sides of the heat exchange plate 30 by welding, brazing, or other methods. The arrangement of the fins 32 directly serves to improve the heat transfer density of the condensation section. When the gaseous phase change fluid rises in the first flow cavity 31 inside the heat exchange plate 30 to the upper part located in the upper heat exchange cavity 11, the heat is transferred through the wall of the heat exchange plate 30 to the fins 32 on the outer surface, and then carried away by the fluid to be heat exchanged flowing over the surface of the fins 32, thereby achieving efficient heat exchange. The height, thickness, and spacing of the fins 32 can be set according to the actual heat exchange requirements, fluid flow rate, and pressure drop limitations. For example, they can be straight fins 32 arranged at equal intervals, or they can be fins 32 with varying density.

[0072] When the fins 32 are arranged parallel to the flow direction, the plate surface of the fins 32 is basically aligned with the fluid flow direction, allowing the fluid to flow smoothly through the channels between adjacent fins 32. This minimizes flow resistance and is suitable for operating conditions with strict pressure drop limitations, effectively preventing severe flow separation or eddy shedding at the root of the fins 32. When the fins 32 are arranged at an angle to the flow direction, they have a certain angle of attack relative to the fluid flow direction. This arrangement induces moderate lateral disturbances and secondary flows as the fluid flows through the fins 32, disrupting the laminar boundary layer on the surface of the heat exchange plate 30 and the fins 32, thinning it, and enhancing the turbulent mixing of the fluid, thereby significantly improving the convective heat transfer coefficient.

[0073] The material of the fins 32 can be the same as that of the heat exchange plate 30, such as stainless steel, carbon steel, or aluminum alloy, which are metals with good thermal conductivity. Alternatively, different materials can be selected based on corrosion resistance or cost considerations, as long as good thermal conductivity is ensured between the two. Besides the common rectangular flat plate shape, the shape of the fins 32 can also be corrugated, serrated, or perforated, as long as its overall extension trend meets the requirement of being parallel or inclined to the fluid flow direction. The fins 32 are only installed in the upper region of the heat exchange plate 30 within the upper heat exchange chamber 11, i.e., the condensation section. The lower evaporation section located in the flue gas passage 21 of the lower heat exchange box 20 typically does not have fins 32 to avoid dust accumulation or high-temperature oxidation in the flue gas. Of course, if special operating conditions require it, installing an enhanced heat transfer structure in the lower part is also within the scope of this application.

[0074] The fluid to be heat-exchanged enters through the fluid inlet 12 of the upper heat exchange chamber 11 and flows through the fluid channel 14 formed on the upper part of the multiple heat exchange plates 30. During this process, the fluid comes into full contact with the fins 32 on both sides of the heat exchange plates 30. If the fins 32 are arranged in parallel, the fluid flows smoothly along the gaps between the fins 32, and the heat is rapidly absorbed through the huge extended surface area, causing the fluid temperature to gradually rise. Meanwhile, the gaseous phase change fluid inside the heat exchange plates 30 releases latent heat and condenses into a liquid state, flowing back to the lower part along the inner wall of the first flow chamber 31 under the action of gravity. If the fins 32 are arranged at an angle, the fluid is disturbed when flowing through the fins 32, the boundary layer is constantly renewed, and the heat exchange efficiency is further improved. Although the flow resistance increases slightly, the heat exchange performance is maximized within the allowable pressure drop range. Throughout the process, the fins 32, as key enhanced heat transfer elements, work together with the heat exchange plate 30 body to ensure the efficient and stable operation of the phase change cycle.

[0075] Through the above scheme, fins 32 are set on the upper front and back surfaces of the heat exchange plate 30, and the fins 32 are set to be parallel or inclined to the flow direction of the fluid to be heat exchanged, thereby greatly expanding the heat exchange area of ​​the condensation section and making up for the insufficient heat exchange capacity of a single flat plate surface. Due to the specific orientation design of the fins 32, the fluid can obtain a sufficient heat exchange interface when flowing through the heat exchange area, while maintaining low flow resistance or enhancing heat transfer through moderate disturbance. Therefore, the problem of low heat exchange density in a limited space of traditional flat plate heat exchangers is solved, and the technical effect of significantly improving the overall heat exchange efficiency and temperature control accuracy is achieved without significantly increasing the equipment volume and fluid transport energy consumption.

[0076] Based on any of the above embodiments, multiple upper heat exchange chambers 11 are provided and isolated from each other. The multiple upper heat exchange chambers 11 are arranged sequentially along the flue gas flow direction, and the upper part of the heat exchange plate 30 extends into each upper heat exchange chamber 11.

[0077] The upper heat exchange chamber 11 being multiple and mutually isolated means that the originally single internal space of the upper heat exchange box 10 is divided into two or more independent chambers by setting up a partition structure. These chambers are completely isolated in physical space, with no direct gas or fluid communication channels between them. This state of mutual isolation means that pressure changes, fluid leaks, or temperature fluctuations in any upper heat exchange chamber 11 are structurally confined within that chamber and will not directly diffuse to adjacent upper heat exchange chambers 11.

[0078] Multiple upper heat exchange chambers 11 arranged sequentially along the flue gas flow direction can mean that these independent upper heat exchange chambers 11 are located above the lower heat exchange box 20, arranged one after another according to the path of the flue gas flowing from the inlet to the outlet. For example, if the flue gas flows from left to right, the first upper heat exchange chamber 11 is located on the far left, the second is adjacent to its right, and so on. This arrangement ensures that the area of ​​the lower flue gas channel 21 corresponding to each upper heat exchange chamber 11 corresponds precisely to different temperature segments in the flue gas flow. Since the flue gas continuously releases heat as it flows through the heat exchange plate 30, its temperature gradually decreases along the flow direction. Therefore, the multiple upper heat exchange chambers 11 arranged sequentially along the flue gas flow direction naturally form a staged condensation region that matches the flue gas temperature gradient. The upper heat exchange chamber 11 located upstream of the flue gas faces the high-temperature flue gas, while the upper heat exchange chamber 11 located downstream faces the low-temperature flue gas.

[0079] Each independent upper heat exchange chamber 11 contains a condensation section of a heat exchange plate 30 responsible for heat exchange in that area. The lower part of the heat exchange plate 30 is located in the flue gas passage 21, absorbing heat from the flue gas and causing the internal phase change fluid to vaporize and rise. The upper part extends into the specific upper heat exchange chamber 11, transferring this heat to the fluid to be heat exchanged within that chamber. Since the upper heat exchange chambers 11 are isolated from each other, the upper part of the heat exchange plate 30 extending into them only exchanges heat with the fluid to be heat exchanged within that specific chamber, without mixing or direct thermal coupling with the fluids in other chambers.

[0080] Through the above technical solution, the upper heat exchange space is divided into multiple independent modules. Utilizing the characteristic of flue gas temperature decreasing along the flow path, a graded heat exchange system matching the heat source temperature gradient is constructed. Because multiple mutually isolated upper heat exchange chambers 11 are arranged sequentially along the flue gas flow direction, the fluid to be heat exchanged can absorb heat energy of different grades at each stage, effectively reducing local thermal stress impact and improving heat exchange uniformity. Simultaneously, due to the physical independence of each chamber, when a module fails, the fault is confined to a local area, avoiding the risk of a single failure causing a complete system shutdown, thereby significantly improving the reliability and fault tolerance of the equipment.

[0081] like Figure 2 As shown, based on the above embodiment, adjacent upper heat exchange chambers 11 can be connected by connecting pipes 15, so that the fluid to be heat exchanged flows through each upper heat exchange chamber 11 in sequence, forming a heat exchange channel connected in series.

[0082] The connecting pipe 15 is a flow guiding component used to connect two adjacent and independent upper heat exchange chambers 11. Both ends of the connecting pipe 15 are sealed to the fluid outlets 13 and fluid inlets 12 on the two adjacent upper heat exchange chambers 10, respectively, or they pass through the sidewalls of the upper heat exchange chambers 10 and directly communicate with the interior of the upper heat exchange chamber 11. The material of the connecting pipe 15 can be the same as that of the upper heat exchange chambers 10, such as carbon steel or stainless steel, or a corrosion-resistant material such as titanium alloy or fluoropolymer-lined pipe can be selected depending on the corrosiveness of the fluid to be exchanged. The cross-sectional shape of the connecting pipe 15 can be circular, rectangular, or other shapes adapted to fluid flow. Its flow cross-sectional area can be set according to the flow rate requirements, and is generally not less than the fluid inlet and outlet cross-sectional areas of the upper heat exchange chamber 11 to reduce local resistance losses.

[0083] In this design, the connecting pipe 15 acts as a fluid bridge between multiple heat exchange units. It guides the heat-exchange fluid, which has already absorbed some heat and flows out of the upper heat exchange chamber 11 of the previous stage, to the upper heat exchange chamber 11 of the next stage to continue participating in heat exchange. Through its cooperation with the upper heat exchange chamber 11, the connecting pipe 15 enables multiple originally independent heat exchange modules to form a logical series relationship in the fluid path, ensuring that the heat-exchange fluid flows through each heat exchange area in a preset order, thereby achieving the gradual accumulation and absorption of heat at each stage.

[0084] Specifically, the fluid to be heat-exchanged enters through the fluid inlet 12 of the first upper heat exchange chamber 11, where it undergoes a first heat exchange with the upper part of the heat exchange plate 30 extending into it, absorbing the heat released by the condensation of the phase change fluid and thus increasing in temperature. Subsequently, the heated fluid is transported via the connecting pipe 15 to the adjacent second upper heat exchange chamber 11, where it undergoes a second heat exchange with the upper part of the heat exchange plate 30 at the corresponding temperature range, further increasing in temperature. This process continues, with the fluid flowing sequentially through all the upper heat exchange chambers 11 connected in series by the connecting pipes 15, absorbing heat each time it passes through a chamber, until it exits from the fluid outlet 13 of the last upper heat exchange chamber 11. Throughout the process, the connecting pipes 15 act as interstage channels, ensuring the continuity and directionality of the fluid flow, allowing the heat from the flue gas at different temperature gradients to be extracted by the fluid in an orderly and graded manner, avoiding problems such as excessive temperature differences or insufficient heat exchange in a single stage.

[0085] The above technical solution extends the heat exchange path of the fluid to be heat exchanged, allowing it to pass through multiple heat exchange units in different temperature zones sequentially. This significantly increases the final outlet temperature and overcomes the problem of insufficient temperature rise caused by temperature difference limitations in single-stage heat exchange. Simultaneously, this step-by-step series connection method allows for more efficient utilization of heat, improving overall heat exchange efficiency. Furthermore, external connecting pipes 15 can be used for series connection, enabling each heat exchange chamber to be prefabricated and tested as an independent module. On-site system expansion requires only the assembly of connecting pipes 15, greatly enhancing the equipment's engineering adaptability and modular maintenance capabilities.

[0086] For the structure of heat exchange plate 30, such as Figure 5 , Figure 6 As shown, the heat exchange plate 30 can be made by welding two thin plates 33 together with several welding parts 34, and the unwelded parts of the two thin plates 33 are far apart to form a first flow cavity 31.

[0087] The two thin plates 33 refer to the metal plates that form the basic structure of the heat exchange plate 30. Their material can be stainless steel, carbon steel, or aluminum alloy, or other metal materials with good thermal conductivity and weldability. The thickness of the thin plates 33 can be set according to the pressure level and heat exchange requirements under actual operating conditions; for example, it can be any value between 0.5 mm and 3 mm. These two thin plates 33 serve as the wall carriers forming the first flow cavity 31, respectively constituting the opposite side walls of the phase change fluid flow channel. The surface flatness of these plates directly affects the uniformity of subsequent blow molding.

[0088] The welded portion 34 is a localized fixed connection point or connecting line formed by resistance welding, laser welding, or brazing after two thin plates 33 are stacked. The distribution and layout of the welded portions 34 on the plane determines the final shape and flow channel direction of the first flow cavity 31. For example, the welded portions 34 can be distributed in a grid pattern, dividing the unwelded area into multiple independent cells; they can also be distributed in a parallel line pattern, forming a long strip flow channel; or they can be distributed in a specific curved pattern to guide the phase change fluid to generate a specific flow path. The welded portion 34 not only connects the two thin plates 33 to prevent them from separating under high pressure, but also acts as a supporting frame to maintain the overall structural strength of the heat exchange plate 30 and prevent it from undergoing excessive deformation under the action of internal and external pressure differences.

[0089] The unwelded portions are separated to form a first flow cavity 31, which can be achieved through a blow molding process to change the physical state. In the specific manufacturing process, two thin plates 33 are first welded together at predetermined positions to form a slab. Then, high-pressure gas (such as compressed air or nitrogen) is introduced into the slab. Under the internal pressure, the area not fixed by the welded portion 34 undergoes plastic deformation and expands outward, causing the two thin plates 33 to separate in this area, thus forming a first flow cavity 31 with a specific volume and cross-sectional shape. This first flow cavity 31 is a closed internal space used to contain the phase change fluid. This formation method makes the inner wall of the first flow cavity 31 smooth and continuous, without obvious steps or weld protrusions, which helps reduce the flow resistance of the phase change fluid during evaporation and condensation, and promotes smooth reflux of the condensate.

[0090] The manufacturing process of welding and blowing two thin plates 33 avoids the high costs and complex procedures associated with traditional machining of deep grooves or brazing of multi-layer plates, thus achieving the technical effects of reducing manufacturing costs and improving production efficiency. Since the first flow cavity 31 is formed by the plastic deformation of the plate itself, the inner wall is smooth and there are no splicing welds, which reduces the flow resistance and dust accumulation risk of the phase change fluid, thus achieving the technical effects of improving heat exchange efficiency and circulation stability. Since the heat exchange plate 30 is integrally formed, the structure has good continuity, and the welded parts 34 are evenly distributed and provide reliable support, thus achieving the technical effects of enhancing the structural strength and sealing reliability of the equipment.

[0091] Based on any of the above embodiments, a partition 40 is provided between the upper heat exchange box 10 and the lower heat exchange box 20, and the heat exchange plate 30 passes through the partition 40, and the heat exchange plate 30 and the partition 40 are sealed together.

[0092] The partition 40 is a physical separation component disposed between the upper heat exchange box 10 and the lower heat exchange box 20, used to completely isolate the flue gas passage 21 in the upper heat exchange chamber 11 and the lower heat exchange box 20. The partition 40 can be made of metal sheet or other high-temperature and corrosion-resistant materials, and its shape and size can be set according to the actual internal space structure of the upper heat exchange box 10 and the lower heat exchange box 20. For example, it can be a flat plate structure or an irregular structure adapted to the outline of the box.

[0093] The baffle 40, as a static support base, provides mechanical fixation support for the heat exchange plate 30 that runs through it, enabling it to withstand the stress and fluid pressure generated by thermal expansion and contraction during operation. Simultaneously, as part of the sealing interface, the baffle 40, through its tight connection with the heat exchange plate 30, blocks direct communication between the flue gas side and the side of the fluid to be exchanged, preventing flue gas from entering the upper heat exchange chamber 11 and contaminating the fluid, and also preventing the fluid to be exchanged from leaking into the flue gas passage 21. Through this combination, the baffle 40 achieves environmental isolation between the upper and lower working areas and structural stability of the heat exchange plate 30.

[0094] The heat exchange plate 30 penetrating the partition 40 refers to the spatial layout where the heat exchange plate 30 extends upward from the lower heat exchange box 20, passes through the partition 40, and enters the upper heat exchange box 10. The shape of the heat exchange plate 30 at the penetration point can be set according to actual design requirements. For example, it can maintain its original flat cross-section or undergo local reinforcement treatment in the penetration area. As the core carrier of heat transfer, the heat exchange plate 30 absorbs heat at its lower part in the flue gas passage 21 and releases heat at its upper part in the upper heat exchange chamber 11. The part penetrating the partition 40 is the key transition area connecting the upper and lower sections. Through this penetrating and sealed connection method, the heat exchange plate 30 not only completes the heat transfer path from bottom to top but also uses its own structural continuity to replace the complex connecting pipes in the traditional split structure, reducing connection nodes.

[0095] The sealing connection method can be selected according to the actual working conditions and manufacturing process. For example, it can be welding sealing, flange gasket sealing, or filling with high-temperature resistant sealant. Preferably, the sealing connection adopts welding, that is, continuous welding is performed on the circumferential edge of the heat exchange plate 30 passing through the partition plate 40 to form a complete weld. It firmly locks the heat exchange plate 30 to the partition plate 40, restricting the displacement of the heat exchange plate 30 in the vertical or horizontal direction; at the same time, it fills the possible small gaps between the heat exchange plate 30 and the partition plate 40, and constructs a barrier for airtightness and liquid tightness. Through this sealing connection, the sealing task of the entire system is concentrated on this single annular interface, avoiding the cumulative leakage risk caused by multi-point sealing, and ensuring the cleanliness of the upper heat exchange chamber 11 and the vacuum degree of the first flow chamber 31.

[0096] Because a baffle 40 is installed and the heat exchange plate 30 is sealed through the baffle 40, the upper heat exchange chamber 11 and the flue gas passage 21 are physically isolated, completely blocking the risk of cross-contamination between the flue gas and the fluid to be heat exchanged. Because the connection between the heat exchange plate 30 and the baffle 40 is sealed in a centralized manner, the sealing requirements that were originally scattered across multiple connection nodes are integrated into a single annular sealing interface, thereby greatly reducing the number of potential leakage points and improving the overall sealing reliability and long-term operational stability of the equipment. At the same time, the baffle 40 provides effective mechanical support for the heat exchange plate 30, enabling it to withstand thermal stress and fluid pressure, ensuring the integration and safety of the heat exchange structure.

[0097] Furthermore, the partition plate 40 is provided with slots through which the heat exchange plate 30 passes, and the heat exchange plate 30 and the slots are sealed by welding.

[0098] In this context, a slot refers to a through hole formed in the partition plate 40, the shape and size of which can be adapted to the cross-sectional profile of the heat exchange plate 30. The slot provides a guiding and positioning reference for the heat exchange plate 30 to pass through the partition plate 40, enabling the heat exchange plate 30 to accurately penetrate to the predetermined position. The heat exchange plate 30 passes through the slot, and the inner wall of the slot forms a tight abutment or a small gap fit with the outer surface of the heat exchange plate 30. This fit allows the heat exchange plate 30 to achieve high-precision automatic alignment during installation without the need for additional positioning clamps or alignment adjustments. The specific shape of the slot can be set according to the actual cross-sectional shape of the heat exchange plate 30, for example, it can be rectangular, elliptical, or an irregular shape consistent with the edge profile of the heat exchange plate 30. Through the slot, the heat exchange plate 30 can smoothly pass through the partition plate 40 under the action of gravity or external force, and initially separates the flue gas passage 21 of the lower heat exchange box 20 from the upper heat exchange chamber 11 in physical space.

[0099] The welding seal is a continuous annular welding operation performed along the circumference of the intersection between the slot and the heat exchange plate 30. The function of this welding seal is to firmly fix the heat exchange plate 30 to the partition plate 40 and simultaneously achieve airtight isolation between the lower heat exchange box 20 and the upper heat exchange cavity 11. In this design, the slot provides a regular trajectory boundary for welding, and the heat exchange plate 30 serves as the fusion base for the welded parts. The combination of these two elements results in a single closed loop for the welding path, without interruption or intersection. This structure allows the welding operation to be completed in one go using automated equipment, resulting in stable and reliable weld quality. The specific implementation method of the welding seal can be selected according to the actual working conditions; for example, it can be argon arc welding, laser welding, or plasma welding, as long as a dense metallurgical bond can be formed. Through this welding seal, the heat exchange plate 30 not only gains mechanical support to withstand the thermal stress and fluid pressure during operation but also completely blocks the path of flue gas entering the upper heat exchange cavity 11 or the fluid to be exchanged leaking to the flue gas channel 21, achieving a triple function of mechanical fixation, environmental isolation, and media sealing.

[0100] The above technical solutions achieve a through-connection effect that is easy to assemble, precise in positioning, and reliable in sealing. Because of the slots that fit the cross-section of the heat exchange plate 30, the heat exchange plate 30 can automatically align when passing through the partition plate 40, eliminating manual adjustment errors and achieving high positioning accuracy. The continuous annular welding seal along the junction ensures a regular and closed welding path, suitable for automated operation, resulting in stable weld quality and high production efficiency. Integrating mechanical fixing, environmental isolation, and media sealing into the same welding process reduces the number of parts and assembly steps, achieving a compact structure, low leakage risk, and high long-term operational reliability.

[0101] The above description is only a specific embodiment of the present utility model, but the technical features of the present utility model are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present utility model are covered by the patent scope of the present utility model.

Claims

1. A vacuum plate heat exchanger, comprising an upper heat exchange box (10) and a lower heat exchange box (20), wherein the upper heat exchange box (10) is provided with an upper heat exchange cavity (11), the lower heat exchange box (20) has a flue gas passage (21), and a heat exchange plate (30) is provided in the lower heat exchange box (20), the lower part of the heat exchange plate (30) is located in the flue gas passage (21), and a vertical first flow cavity (31) is formed inside the heat exchange plate (30), wherein the first flow cavity (31) contains a phase change fluid; characterized in that The upper part of the heat exchange plate (30) extends into the upper heat exchange cavity (11), which has a fluid inlet (12) and a fluid outlet (13) for the fluid to be exchanged to flow in and out; the first flow cavity (31) is isolated from the upper heat exchange cavity (11).

2. A vacuum plate heat exchanger according to claim 1, characterized in that The upper part of the heat exchange plate (30) is flat, and the upper parts of multiple heat exchange plates (30) are parallel to each other and spaced apart. A fluid channel (14) is formed between the upper parts of two adjacent heat exchange plates (30) for the flow of the fluid to be heat exchanged.

3. A vacuum panel heat exchanger according to claim 2, characterised in that The upper part of the heat exchange plate (30) is arranged vertically or inclined so that the phase change fluid in the first flow cavity (31) can flow back to the lower part of the heat exchange plate (30) under the action of gravity after condensation.

4. A vacuum panel heat exchanger according to claim 3, characterised in that The upper part of the heat exchange plate (30) is vertically arranged, and the upper parts of multiple heat exchange plates (30) are arranged in sequence along the horizontal direction.

5. A vacuum panel heat exchanger according to claim 1, characterized in that The heat exchange plate (30) has fins (32) on its upper front and back surfaces. The fins (32) are arranged parallel to or inclined to the flow direction of the fluid to be heat exchanged.

6. A vacuum panel heat exchanger according to claim 1, characterized in that The upper heat exchange chamber (11) is provided in multiple and isolated from each other. The multiple upper heat exchange chambers (11) are arranged in sequence along the flue gas flow direction. The upper part of the heat exchange plate (30) extends into each upper heat exchange chamber (11).

7. A vacuum panel heat exchanger according to claim 6, characterised in that The adjacent upper heat exchange chambers (11) are connected by a connecting pipe (15), so that the fluid to be heat exchanged flows through each upper heat exchange chamber (11) in sequence, forming a heat exchange channel connected in series.

8. A vacuum panel heat exchanger according to claim 1, characterized in that The heat exchange plate (30) is formed by welding two thin plates (33) together through several welding parts (34). The unwelded parts of the two thin plates (33) are far apart from each other to form a first flow cavity (31).

9. A vacuum panel heat exchanger according to claim 1, characterized in that A partition (40) is provided between the upper heat exchange box (10) and the lower heat exchange box (20). The heat exchange plate (30) passes through the partition (40), and the heat exchange plate (30) and the partition (40) are sealed together at the point of penetration.

10. A vacuum panel heat exchanger according to claim 9, characterized in that The partition plate (40) is provided with a slot through which the heat exchange plate (30) passes, and the heat exchange plate (30) and the slot are sealed by welding.

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