Liquid material distribution device of heat exchange tube enhanced heat transfer type falling film evaporator

Abstract

The invention relates to the technical field of falling-film evaporators, in particular to a liquid material distribution device of a heat exchange tube enhanced heat transfer type falling-film evaporator, which comprises a falling-film evaporator shell, the falling-film evaporator shell consists of a top-section cover shell and a middle-section cover shell, and a plurality of groups of heat exchange tubes are arranged in an inner cavity of the middle-section cover shell. A sealing cover, a buffer plate and a liquid distribution disc are arranged in an inner cavity of the top-section cover shell, a main liquid distribution hole is formed in the top of the liquid distribution disc in a penetrating mode, the bottom end of the sealing cover is in sealed connection with the inner side wall of the top-section cover shell, and the outer side wall of the buffer plate and the outer side wall of the liquid distribution disc arranged below the buffer plate are both in sealed connection with the inner side wall of the top-section cover shell; according to the device, by means of the three-section type composite liquid distribution holes, the inner wall spiral guide grooves, the partition pressure control nozzles and the annular flow channel material supplementing structure, liquid material surface tension is cooperatively broken, liquid film uniform distribution is accurately regulated and controlled, efficient liquid distribution and enhanced heat transfer of the heat exchange pipe are achieved, and the evaporation efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of falling film evaporator technology, specifically to a liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator. Background Technology

[0002] Falling film evaporators are widely used in solution concentration, solvent recovery, and wastewater treatment processes in chemical, food, pharmaceutical, and seawater desalination industries due to their advantages of high heat transfer coefficient, short material residence time, and low energy consumption. The core of the process is to uniformly distribute the liquid to be treated on the inner wall of the heat exchange tube to form a thin liquid film. Rapid evaporation and separation are achieved through heat exchange between the liquid film and the heating medium on the outside of the heat exchange tube. The uniformity of the liquid distribution on the inner wall of the heat exchange tube directly determines the heat transfer efficiency, product quality, and operational stability of the equipment. Significant defects exist in the liquid distribution process of falling film evaporators. The core problem is the lack of an effective pressure control mechanism and insufficient response to the surface tension of the liquid, ultimately leading to uneven liquid film thickness and limiting equipment efficiency. In the patent application number 2020223359857, the upper / lower distribution plate, guide rod, and drop pipe structure rely solely on baffle diversion and gravity discharge, lacking active pressure control. On the one hand, gravity drive cannot compensate for pressure loss along the flow path, resulting in insufficient liquid power in the edge areas, easily leading to stagnation or material shortage. On the other hand, the lack of a targeted surface tension breaking design makes the liquid easily adhere to the walls of the distribution holes, hindering feeding, and secondary steam turbulence further degrades the stability of the liquid distribution. In addition, its flow guiding and distribution structure design is unreasonable, resulting in uneven liquid diffusion and large feeding deviations in each distribution hole, ultimately leading to significant differences in the liquid film thickness on the inner wall of the heat exchange tube, with some areas having excessively thick liquid films or dry walls, severely affecting heat transfer efficiency and evaporation effect.

[0003] Therefore, it is necessary to develop a liquid distribution device for falling film evaporators with active pressure regulation. By pressurizing and stabilizing, partitioning and compensating for losses, and breaking surface tension, a uniform and continuous liquid film can be achieved, solving the liquid distribution defects of existing technologies and improving heat transfer efficiency and stability. Summary of the Invention

[0004] The purpose of this invention is to provide a liquid distribution device for a heat exchange tube enhanced heat transfer falling film evaporator, which solves the problems mentioned in the background art above.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A liquid distribution device for a heat exchange tube enhanced heat transfer falling film evaporator includes a falling film evaporator shell, which is composed of a top section shell and a middle section shell. The inner cavity of the middle section shell is provided with multiple sets of heat exchange tubes, and the inner cavity of the top section shell is provided with a sealing cover, a buffer plate, and a liquid distribution plate. The top of the liquid distribution plate has a main liquid distribution hole.

[0006] Furthermore, the bottom end of the sealing cover is sealed to the inner wall of the top section cover, the outer wall of the buffer plate and the outer wall of the liquid distribution plate below it are sealed to the inner wall of the top section cover, and the top end of the buffer plate is provided with a through hole corresponding to the position of the main liquid distribution hole.

[0007] Furthermore, the top of the liquid distribution plate is provided with main liquid distribution holes, which are arranged in multiple concentric ring arrays along the direction from the center to the edge of the liquid distribution plate, and the diameter of the main liquid distribution holes on each ring array gradually increases from the center to the edge.

[0008] Furthermore, the main liquid distribution hole has a three-section composite structure, with an expansion section at the top, a contraction section in the middle, and a gradually expanding section at the bottom, and each section has a smooth transition; each heat exchange tube is positioned directly above a main liquid distribution hole to ensure that the liquid flows directly to the inner wall of the corresponding heat exchange tube after being guided by the main liquid distribution hole. Furthermore, the inner wall of the main liquid distribution hole is provided with an inner spiral guide groove. The inner spiral guide groove extends spirally downward along the inner wall of the hole from the upper inlet to the lower outlet of the hole, and closely fits the variable diameter profile of the composite hole throughout the entire process. In the duct expansion section, the depth of the inner spiral guide groove is adjusted synchronously as the duct diameter increases. In the duct contraction section, the depth of the inner spiral guide groove is reduced accordingly as the duct diameter decreases, so that the inner spiral guide groove and the inner wall of the duct always form a continuous flow channel.

[0009] Furthermore, an annular groove is formed at the top of the inlet end of the main liquid distribution hole. The annular groove is coaxially arranged with the main liquid distribution hole, and the width of the annular groove is adapted to the diameter of the main liquid distribution hole, which is one-fifth to one-third of the diameter of the main liquid distribution hole.

[0010] Furthermore, the top of the liquid distribution plate is uniformly provided with multiple sets of guide grooves from its center to the edge. The center line of each set of guide grooves is located at the exact middle of two adjacent main liquid distribution holes in the same annular array, and does not coincide with the center of any main liquid distribution hole. The extension path of the guide channel is from the center of the liquid distribution plate to the edge, and the depth of the guide channel gradually increases along the extension direction.

[0011] Furthermore, each of the main liquid distribution holes is equipped with a nozzle at its inlet, and the liquid distribution plate is provided with an annular flow channel corresponding to each ring of main liquid distribution holes. The annular flow channel is connected to the annular groove and guide groove at the inlet of the corresponding main liquid distribution hole. An auxiliary liquid distribution groove is provided between adjacent main liquid distribution holes in the edge area of ​​the liquid distribution plate, and the auxiliary liquid distribution groove is connected to the annular flow channel of its ring.

[0012] Furthermore, the top and outer walls of the top section cover are respectively connected to a feed pipe and a gas guide pipe. The bottom end of the feed pipe extends into the interior of the sealing cover, and one end of the gas guide pipe extends into the interior of the sealing cover. A housing is provided on one side of the falling film evaporator shell, and one end of the gas guide pipe extends into the housing. The nozzle is connected to the interior of the housing through a micro-pipe.

[0013] Furthermore, the middle section cover is fixedly connected to partitions near the top and bottom of its inner cavity, and the heat exchange tube is sleeved and fixed in the mounting groove of the partition. The top and bottom of the side wall of the middle section cover are respectively connected to an upper channel and a lower channel, and the bottom of the middle section cover is connected to two connecting pipes, one end of which is connected to the liquid storage tank.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention regulates the base pressure and zoned pressure supplementation by a graded variable frequency booster pump, and is driven smoothly by inert gas. This avoids liquid pulse flow caused by pressure fluctuations, and precisely helps the liquid overcome surface tension and enter the distribution hole through the oblique thrust of the nozzle. At the same time, it compensates for pressure loss along the process, ensuring that the liquid entering the hole in the central area and the edge area has consistent power, thereby reducing the liquid distribution deviation caused by uneven power from the source.

[0015] The radial guide channel with gradually varying depth reduces frictional resistance and prevents liquid stagnation at the edges. The annular flow channel ensures uniform distribution of liquid in the same ring of distribution holes, and the auxiliary distribution channel replenishes the liquid in the edge area, eliminating distribution gaps and excessively thin liquid films, significantly reducing the overall distribution deviation. At the same time, the composite channel, combined with the spiral guide channel, breaks tension and improves the uniformity of falling film: the three-section composite channel increases the liquid flow rate to overcome tension through the Venturi effect, and the gradually expanding section ensures precise guidance; the centrifugal force generated by the spiral guide channel breaks the continuity of surface tension, preventing liquid from adhering to the hole wall, and at the same time makes the liquid form a spiral liquid flow that evenly adheres to the inner wall of the heat exchange tube, forming a continuous and unbroken uniform falling film. Attached Figure Description

[0016] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings; Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram showing the installation positions of the upper and lower channels in this invention; Figure 3 This is a schematic diagram of the heat exchange tube structure in this invention; Figure 4 This is a schematic diagram of the liquid storage tank structure in this invention; Figure 5 This is a schematic diagram of the sealing cover structure in this invention; Figure 6This is a schematic diagram of the buffer plate structure in this invention; Figure 7 This is a schematic diagram of the top structure of the liquid distribution plate in this invention; Figure 8 This is a cross-sectional view of the variable diameter profile of the main liquid distribution hole and the inner spiral guide groove in this invention. Figure 9 This is a schematic diagram of the bottom structure of the liquid distribution plate in this invention.

[0017] Reference numerals: 101, Top section cover; 102, Middle section cover; 2, Heat exchange tube; 3, Sealing cover; 4, Buffer plate; 5, Liquid distribution tray; 6, Main liquid distribution hole; 7, Guide channel; 8, Nozzle; 9, Annular flow channel; 10, Auxiliary liquid distribution channel; 11, Feed pipe; 12, Air guide pipe; 13, Baffle plate; 141, Upper channel; 142, Lower channel; 15, Connecting pipe; 16, Liquid storage tank; 17, Chassis; 18, Miniature through pipe. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: As Figure 1 - Figure 9 As shown, the core working logic of the liquid distribution device of this heat exchange tube enhanced heat transfer falling film evaporator is to achieve uniform falling film and efficient evaporation of liquid on the inner wall of the heat exchange tube through a coordinated process of closed pressurization drive, precise liquid distribution, efficient heat exchange evaporation, and stable pressure regulation, ensuring sealing performance and operational stability throughout the process. Specifically, it includes the outer shell of a falling film evaporator, which consists of a top section shell 101 and a middle section shell 102. The top section shell 101 and the middle section shell 102 of the falling film evaporator shell are rigidly sealed together by a flange structure with a sealing ring, ensuring that the inner cavity of the whole machine forms an absolutely sealed space. This eliminates the pressure instability caused by gas leakage during subsequent pressurization, as well as the material loss and safety hazards caused by liquid overflow. The inner cavity of the middle section shell 102 is equipped with multiple sets of heat exchange tubes 2, and the inner cavity of the top section shell 101 is equipped with a sealing cover 3, a buffer plate 4, and a liquid distribution plate 5. The bottom end of the sealing cover 3 is sealed with the inner side wall of the top section shell 101 by an interference fit of an annular rubber sealing ring. The outer side walls of the buffer plate 4 and the liquid distribution plate 5 are fixedly connected to the inner side wall of the top section shell 101 by sealing with sealing rings, thus constructing a sealed cavity that is independent of each other but interconnected at each level.

[0020] The top of the liquid distribution plate 5 is provided with a main liquid distribution hole 6. The bottom end of the sealing cover 3 is sealed to the inner wall of the top section cover 101. The outer wall of the buffer plate 4 and the outer wall of the liquid distribution plate 5 below it are sealed to the inner wall of the top section cover 101. The top of the buffer plate 4 is provided with a through hole corresponding to the position of the main liquid distribution hole 6.

[0021] The liquid distribution plate 5 has a main liquid distribution hole 6 at the top. The main liquid distribution holes 6 are arranged in multiple concentric ring arrays along the direction from the center to the edge of the liquid distribution plate 5. The diameter of the main liquid distribution holes 6 on each ring array gradually increases from the center to the edge.

[0022] The main liquid distribution hole 6 has a three-section composite structure, with an expansion section at the top, a contraction section in the middle, and a gradually expanding section at the bottom, and each section has a smooth transition. The main liquid distribution hole 6 is set one-to-one with the top of each heat exchange tube 2 to ensure that the liquid flows directly to the inner wall of the corresponding heat exchange tube 2 after being guided by the main liquid distribution hole 6. The inner wall of the main liquid distribution hole 6 is provided with an inner spiral guide groove. The inner spiral guide groove extends spirally downward along the inner wall of the hole from the upper inlet to the lower outlet of the hole, and closely fits the variable diameter profile of the composite hole throughout the entire process. In the duct expansion section, the depth of the inner spiral guide groove is adjusted synchronously with the increase of the duct diameter. In the duct contraction section, the depth of the inner spiral guide groove is reduced accordingly with the decrease of the duct diameter, so that the inner spiral guide groove and the inner wall of the duct always form a continuous flow channel.

[0023] Example 2: A ring-shaped groove is formed at the top of the inlet end of the main liquid distribution hole 6. The ring-shaped groove is coaxial with the main liquid distribution hole 6, and the width of the ring-shaped groove is adapted to the diameter of the main liquid distribution hole 6, which is one-fifth to one-third of the diameter of the main liquid distribution hole 6. On the top of the liquid distribution plate 5, multiple sets of guide grooves 7 are evenly distributed from its center to its edge. The center line of each set of guide grooves 7 is located at the exact middle of two adjacent main liquid distribution holes 6 in the same ring array, and does not coincide with the center of any main liquid distribution hole 6. The extension path of the guide groove 7 is from the center of the liquid distribution plate 5 to the edge, and the depth of the guide groove 7 gradually increases along the extension direction. A nozzle 8 is provided at the inlet of each main liquid distribution hole 6. An annular flow channel 9 is provided on the liquid distribution plate 5 corresponding to each ring of main liquid distribution holes 6. The annular flow channel 9 is connected to the annular groove and guide groove 7 at the inlet of the corresponding main liquid distribution hole 6. An auxiliary liquid distribution groove 10 is provided between adjacent main liquid distribution holes 6 in the edge area of ​​the liquid distribution plate 5. The auxiliary liquid distribution groove 10 is connected to the annular flow channel 9 of its ring.

[0024] The top and outer walls of the top section cover 101 are respectively connected to the feed pipe 11 and the air guide pipe 12. The bottom end of the feed pipe 11 extends into the interior of the sealing cover 3, and one end of the air guide pipe 12 extends into the interior of the sealing cover 3. A housing 17 is provided on one side of the falling film evaporator shell. One end of the air guide pipe 12 extends into the interior of the housing 17. The nozzle 8 is connected to the interior of the housing 17 through the micro-connecting pipe 18.

[0025] It needs to be explained here that multiple variable frequency booster pumps are installed inside the chassis 17. One of the variable frequency booster pumps is connected to the sealing cover 3 through the air guide pipe 12. The connection between the air guide pipe 12 and the top cover 101 and the sealing cover 3 is sealed. The other variable frequency booster pumps are connected to each nozzle 8 through the micro pipe 18 to ensure that there is no leakage in the pressurization channel.

[0026] Partition plates 13 are fixedly connected to the middle section cover 102 near the top and bottom of its inner cavity. The heat exchange tube 2 is sleeved and fixed in the mounting groove of the partition plate 13. The top and bottom of the side wall of the middle section cover 102 are respectively connected to the upper channel 141 and the lower channel 142. The bottom of the middle section cover 102 is connected to two connecting pipes 15, one end of which is connected to the liquid storage tank 16.

[0027] Combining Embodiment 1 and Embodiment 2, the working principle of the liquid distribution device for the heat exchange tube enhanced heat transfer falling film evaporator is as follows: One end of the feed pipe 11 is connected to the external raw material storage tank, and the other end of the feed pipe 11 passes through the top of the top section cover 101 and the top of the sealing cover 3 in sequence, and sealing rings are installed at the through holes of both. After the external feed pump is started, the liquid to be processed is accurately transported to the inside of the sealing cover 3 through the feed pipe 11. The liquid level is maintained at 2-3 cm inside the sealing cover 3 to complete the feeding preparation and avoid overflow due to excessive liquid level or insufficient pressurization power due to excessively low liquid level.

[0028] Start the corresponding variable frequency booster pump and introduce an inert gas, preferably nitrogen, into the sealing cover 3 through the air guide pipe 12. Nitrogen is chemically stable and will not react with the liquid material to produce oxidation, polymerization or other reactions. Strictly control the pressure fluctuations inside the sealing cover 3 to form a stable basic pressure environment. This provides a continuous and controllable power basis for the smooth diversion of the liquid material and avoids pulse flow of the liquid material caused by pressure fluctuations.

[0029] Under the pressure of inert gas, the liquid in the sealing cover 3 permeates downwards at a uniform speed to the buffer plate 4. When the liquid passes through these evenly distributed through holes, it is further diverted to avoid the liquid from concentrating and impacting the liquid distribution plate 5, which would cause local liquid accumulation. On the other hand, the buffer plate 4 can effectively reduce the impact of pressure fluctuations in the sealing cover 3 on the flow of the liquid, ensuring that the liquid falls smoothly to the top of the liquid distribution plate 5 in a laminar flow state. Simultaneously, other variable frequency booster pumps are started, and pressurized gas is delivered to the nozzles 8 on the liquid distribution plate 5 through the micro-pipe 18. The nozzles 8 are divided into three groups according to the annular array of the main liquid distribution holes 6: the central area, the transition area, and the edge area. Each group is independently pressure controlled. The output pressure of the nozzles 8 in the central area is consistent with the basic pressure inside the sealing cover 3. The pressure in the transition area is higher than that in the central area, and the pressure in the edge area is further increased than that in the transition area. This is to accurately compensate for the pressure loss along the flow of liquid from the center to the edge of the liquid distribution plate 5, and to ensure that the power of liquid entering the main liquid distribution hole 6 in each area is consistent, providing a core guarantee for the uniformity of liquid distribution in the entire area.

[0030] Multiple sets of radial guide channels 7 are evenly distributed on the top of the liquid distribution plate 5. The guide channels 7 extend from the center to the edge, and the depth of the guide channels 7 gradually increases from the center to the edge. This structural design can effectively reduce the frictional resistance of the liquid flow and avoid insufficient power to prevent the liquid from stagnating when it reaches the edge. After the liquid falls to the top of the liquid distribution plate 5, it spreads evenly in all directions along the guide groove 7. Since the center line of the guide groove 7 is exactly in the middle of two adjacent main liquid distribution holes 6 in the same annular array, it will not block or impact the main liquid distribution holes 6, ensuring smooth liquid distribution.

[0031] Each main liquid distribution hole 6 is equipped with an annular flow channel 9, which is connected to the guide groove 7 and the annular groove at the inlet of the main liquid distribution hole 6. The liquid flowing out of the guide groove 7 smoothly flows into the annular flow channel 9 of the corresponding ring. The liquid flow in the annular flow channel 9 achieves uniform distribution of liquid in the main liquid distribution holes 6 of the same ring, reducing the deviation of the feed amount of each main liquid distribution hole 6 in the same ring.

[0032] An auxiliary liquid distribution groove 10 is provided between the edge area of ​​the liquid distribution tray 5 and the adjacent main liquid distribution hole 6. One end of the groove is sealed and connected to the annular flow channel 9 in the edge area, and the other end extends to the edge of the annular groove at the inlet of the main liquid distribution hole 6. When the liquid volume in the edge area is insufficient due to the long liquid flow path, the liquid in the annular flow channel 9 can be quickly replenished to the corresponding main liquid distribution hole 6 through the auxiliary liquid distribution groove 10. This avoids the problem of liquid distribution gaps or excessively thin liquid films in the edge area, thereby reducing the liquid distribution volume deviation between the edge area and the center area and ensuring the integrity of the liquid distribution coverage of the entire area.

[0033] The nozzle 8 opens at an angle of 30° to 45° downwards, precisely aligned with the junction of the annular flow channel 9 and the annular groove at the inlet of the main liquid distribution hole 6. After the pressurized gas is ejected from the nozzle 8, it applies a thrust obliquely along the direction of liquid flow, which helps the liquid to quickly break through the surface tension and enter the main liquid distribution hole 6 without impacting the inside of the channel and causing liquid flow turbulence. The liquid in the auxiliary liquid distribution tank 10 also flows into the main liquid distribution hole 6 simultaneously under the action of gas thrust.

[0034] like Figure 8As shown, the main liquid distribution orifice 6 adopts a three-section composite structure consisting of an upper expansion section, a middle contraction section, and a lower gradually expanding section. The upper expansion section has a 15° cone angle and an inlet diameter 30% larger than the middle contraction section, significantly increasing the liquid contact area and reducing surface tension resistance at the inlet, allowing the liquid to enter the channel quickly. The middle contraction section has a 30% smaller diameter than the inlet, creating a Venturi effect, which, combined with pressurization, increases the liquid flow rate, enabling rapid breakthrough of surface tension constraints. The lower gradually expanding section has a 10° cone angle and an outlet diameter 20% larger than the middle section, effectively preventing excessive diffusion of the liquid after exiting the orifice, ensuring precise guidance of the liquid to the heat exchange tube 2, and controlling the liquid flow diffusion angle at the outlet to within 5°, thus improving guidance accuracy. Simultaneously, the orifice diameter of the main liquid distribution orifice 6 gradually increases from the center of the distribution plate 5 towards the edge, further compensating for pressure loss in the edge area and ensuring consistent liquid flow rate in all areas.

[0035] The inner spiral guide groove of the main liquid distribution hole 6 is a continuous right-hand spiral structure, extending from the upper inlet to the lower outlet, and conforming to the diameter change profile of the channel throughout. The depth of the guide groove in the expansion section increases synchronously with the increase of the hole diameter, and the depth of the guide groove in the contraction section decreases accordingly with the decrease of the hole diameter, ensuring that the flow channel is continuous and uninterrupted. When the liquid flows downward along the spiral guide groove, it will generate centrifugal force. This centrifugal force can effectively disrupt the continuity of surface tension, avoid liquid adhesion to the hole wall and stagnation, and at the same time make the liquid form a spiral liquid flow. After exiting the hole, it flows downward along the inner wall of the heat exchange tube 2, which significantly increases the contact area between the liquid film and the heat exchange tube 2 and reduces the problem of uneven liquid film thickness.

[0036] Since each heat exchange tube 2 is directly opposite the main liquid distribution hole 6, the liquid material is precisely guided to the inner wall of the heat exchange tube 2 below through the gradually expanding section at the lower end of the main liquid distribution hole 6. At the same time, the centrifugal force of the spiral liquid flow makes the liquid material evenly adhere to the inner wall of the heat exchange tube 2, and finally form a falling film with uniform thickness and continuous and unbroken surface, thereby effectively avoiding the decrease in heat transfer efficiency caused by local dry walls or excessively thick liquid films.

[0037] The upper channel 141 at the top of the side wall of the middle section cover 102 is connected to the external hot air furnace or industrial steam boiler through a flange seal. The high-temperature hot gas heating medium enters the outer area of ​​the heat exchange tube 2 inside the middle section cover 102 through the upper channel 141. The high-temperature hot gas flows in a cross-flow state inside the middle section cover 102 and exchanges heat with the liquid falling film on the inner wall of the heat exchange tube 2 to ensure that the liquid evaporates quickly inside the heat exchange tube 2. After the high-temperature hot gas exchanges heat with the liquid, the temperature decreases and the liquid condenses into condensate. The condensate flows along the inner wall of the middle section cover 102 to the bottom, and is sealed and discharged through the lower channel 142 on the side wall. It then flows into the external condensate recovery tank for recycling, thereby improving energy efficiency.

[0038] After absorbing heat, the liquid material on the inner wall of heat exchange tube 2 evaporates rapidly, forming a gas-liquid mixture. The mixture is separated into gas and liquid by gravity settling. Light vapors with low boiling points, such as water and low-boiling-point solvents, rise to the top of the storage tank 16 and are connected to the subsequent condenser or distillation column for further purification through the outer outlet pipe (not shown in the figure). Heavy liquids with high boiling points, such as target concentrates and high-boiling-point impurities, are retained in the lower part of the inner cavity of the middle section cover 102 due to gravity settling, thus completing the evaporation and separation process of the liquid material. During the operation of the whole machine, the corresponding variable frequency booster pumps always coordinate and regulate the pressure: the variable frequency booster pumps continuously maintain the basic stable pressure in the sealing cover 3 through the air guide pipe 12 to ensure that the liquid material stably passes through the buffer plate 4 and flows into the guide channel 7 at a preset flow rate; other variable frequency booster pumps precisely replenish the pressure to each ring nozzle 8 through the micro pipe 18, and compensate for the pressure loss of the liquid material along the flow channel 7 and the annular flow channel 9 in real time, so as to ensure the dynamic balance of the liquid material in the whole area.

[0039] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator, comprising a falling film evaporator shell, wherein the falling film evaporator shell is composed of a top section cover (101) and a middle section cover (102), characterized in that, The inner cavity of the middle section cover (102) is provided with multiple sets of heat exchange tubes (2), and the inner cavity of the top section cover (101) is provided with a sealing cover (3), a buffer plate (4) and a liquid distribution plate (5). The top of the liquid distribution plate (5) is provided with a main liquid distribution hole (6).

2. The liquid distribution device for a heat exchange tube enhanced heat transfer falling film evaporator according to claim 1, characterized in that, The bottom end of the sealing cover (3) is sealed to the inner wall of the top section cover (101). The outer wall of the buffer plate (4) and the outer wall of the liquid distribution plate (5) below it are sealed to the inner wall of the top section cover (101). The top end of the buffer plate (4) is provided with a through hole corresponding to the position of the main liquid distribution hole (6).

3. The liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator according to claim 2, characterized in that, The liquid distribution plate (5) has a main liquid distribution hole (6) at the top. The main liquid distribution hole (6) is arranged in a concentric ring array along the direction from the center to the edge of the liquid distribution plate (5). The diameter of the main liquid distribution hole (6) on each ring array gradually increases from the center to the edge.

4. The liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator according to claim 3, characterized in that, The main liquid distribution hole (6) has a three-section composite structure, with an expansion section at the top, a contraction section in the middle, and a gradually expanding section at the bottom, and each section has a smooth transition. The main liquid distribution hole (6) is set one-to-one with the top of each heat exchange tube (2) to ensure that the liquid flows directly to the inner wall of the corresponding heat exchange tube (2) after being guided by the main liquid distribution hole (6).

5. The liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator according to claim 3, characterized in that, The inner wall of the main liquid distribution hole (6) is provided with an inner spiral guide groove. The inner spiral guide groove extends spirally downward along the inner wall of the hole from the upper inlet of the hole to the lower outlet of the hole, and closely fits the variable diameter profile of the composite hole throughout the entire process. In the duct expansion section, the depth of the inner spiral guide groove is adjusted synchronously as the duct diameter increases. In the duct contraction section, the depth of the inner spiral guide groove is reduced accordingly as the duct diameter decreases, so that the inner spiral guide groove and the inner wall of the duct always form a continuous flow channel.

6. The liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator according to claim 3, characterized in that, A ring groove is provided at the top of the inlet end of the main liquid distribution hole (6). The ring groove is coaxially arranged with the main liquid distribution hole (6), and the width of the ring groove is adapted to the diameter of the main liquid distribution hole (6). Its width is one-fifth to one-third of the diameter of the main liquid distribution hole (6).

7. The liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator according to claim 1, characterized in that, The top of the liquid distribution plate (5) is uniformly provided with multiple sets of guide grooves (7) from its center to its edge. The center line of each set of guide grooves (7) is located in the middle of two adjacent main liquid distribution holes (6) in the same annular array, and does not coincide with the center of any main liquid distribution hole (6). The extension path of the guide groove (7) is from the center of the liquid distribution plate (5) to the edge, and the depth of the guide groove (7) gradually increases along the extension direction.

8. The liquid distribution device for a heat exchange tube enhanced heat transfer falling film evaporator according to claim 3, characterized in that, A nozzle (8) is provided at the inlet of each main liquid distribution hole (6). An annular flow channel (9) is provided on the liquid distribution plate (5) corresponding to each ring of main liquid distribution holes (6). The annular flow channel (9) is connected to the annular groove and guide groove (7) at the inlet of the corresponding main liquid distribution hole (6). An auxiliary liquid distribution groove (10) is provided between adjacent main liquid distribution holes (6) in the edge area of ​​the liquid distribution plate (5). The auxiliary liquid distribution groove (10) is connected to the annular flow channel (9) of the ring.

9. The liquid distribution device for a heat exchange tube enhanced heat transfer type falling film evaporator according to claim 8, characterized in that, The top and outer walls of the top section cover (101) are respectively connected to the feed pipe (11) and the air guide pipe (12). The bottom end of the feed pipe (11) extends into the interior of the sealing cover (3), and one end of the air guide pipe (12) extends into the interior of the sealing cover (3). A housing (17) is provided on one side of the falling film evaporator shell. One end of the air guide pipe (12) extends into the interior of the housing (17). The nozzle (8) is connected to the interior of the housing (17) through a micro-pipe (18).

10. The liquid distribution device for a heat exchange tube enhanced heat transfer falling film evaporator according to claim 1, characterized in that, The middle section cover (102) is fixedly connected to a partition plate (13) near the top of its inner cavity and near the bottom of its inner cavity. The heat exchange tube (2) is sleeved and fixed in the mounting groove of the partition plate (13). The top and bottom of the side wall of the middle section cover (102) are respectively connected to an upper channel (141) and a lower channel (142). The bottom of the middle section cover (102) is connected to two connecting pipes (15). One end of the connecting pipe (15) is connected to the liquid storage tank (16).

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