Falling film type thin film evaporation system and evaporation process

Abstract

The invention relates to a falling film type thin film evaporation system and an evaporation process, and belongs to the technical field of falling film evaporation, the falling film type thin film evaporation system comprises a tank body, multiple thin film sets, a steam compressor, a gas homogenizing mechanism and a condensate collecting mechanism, the multiple thin film sets are arranged in the tank body, the tank body communicates with a liquid inlet pipeline used for feeding liquid, and the condensate collecting mechanism communicates with the liquid inlet pipeline; the input end of the steam compressor is communicated with the tank body, the gas equalizing mechanisms are in one-to-one correspondence with the film groups, the gas equalizing mechanisms are arranged in the corresponding film groups, each gas equalizing mechanism is communicated with the output end of the steam compressor, and the gas equalizing mechanisms are used for uniformly guiding steam output by the steam compressor into the corresponding film groups. The condensate collecting mechanism is arranged on the tank body and used for collecting condensate in the multiple film sets. The method has the effect of saving the cost to a certain extent.

Description

Technical Field

[0001] The present application relates to the technical field of falling film evaporation, and in particular to a falling film thin film evaporation system and an evaporation process. Background Art

[0002] Falling film evaporator is an evaporation device used to treat wastewater in the fields of production industry, chemical industry, life, etc. Its working principle is mainly to add the feed liquid from the upper end of the falling film evaporator, distribute it into the pipeline through the liquid distributor, so that the feed liquid forms a film and flows from top to bottom along the pipeline, and high-temperature water vapor is introduced into the device to perform heat exchange on the feed liquid in the pipeline, so that the feed liquid in the pipeline evaporates and concentrates in this process, and finally obtains concentrated liquid and steam at the bottom of the device, and then separates the steam and concentrated liquid through a separator to obtain concentrated liquid and steam respectively.

[0003] At present, a falling film evaporator usually needs to introduce a large amount of external high-temperature water vapor for a long time to evaporate the liquid in the pipeline, which is very costly. Summary of the Invention

[0004] In order to save costs to a certain extent, the present application provides a falling film thin film evaporation system and evaporation process.

[0005] In a first aspect, the present application provides a falling film thin film evaporation system, which adopts the following technical solution: A falling film thin film evaporation system includes a tank body, a thin film group, a steam compressor, an air equalization mechanism and a condensate collection mechanism. The thin film groups are arranged in multiple groups in the tank body. The tank body is connected to a liquid inlet pipe for feeding liquid. The input end of the steam compressor is connected to the tank body. The air equalization mechanism corresponds to the thin film group one by one. The air equalization mechanism is arranged in the corresponding thin film group. Each of the air equalization mechanisms is connected to the output end of the steam compressor. The air equalization mechanism is used to evenly introduce the steam output by the steam compressor into the corresponding thin film group. The condensate collection mechanism is arranged on the tank body. The condensate collection mechanism is used to collect condensate in multiple groups of thin film groups.

[0006] Preferably, the falling film evaporation system further comprises a first heat exchanger, the first heat exchanger being connected to a steam delivery pipe for delivering external steam, and the first heat exchanger being used to exchange heat between the steam delivered by the steam delivery pipe and the feed liquid entering the liquid inlet pipe.

[0007] Preferably, the plurality of film groups are arranged in two rows and are opposite to each other, and each of the film groups includes a plurality of polymer films sequentially arranged in the tank body along a horizontal direction.

[0008] Preferably, the evaporation system further comprises a water distribution mechanism, the water distribution mechanism corresponding to each membrane group one by one, the water distribution mechanism being located above the corresponding membrane group, and the water distribution mechanism being used to evenly distribute the liquid entering the liquid inlet pipe to the outer wall of the corresponding membrane group; The water equalizing mechanism includes a water equalizing box and a water equalizing bar arranged in the tank body. The liquid in the liquid inlet pipe flows into multiple water equalizing boxes respectively. Multiple water holes are opened on the bottom wall of the water equalizing box. The water equalizing box is located above the water equalizing bar. There are multiple water equalizing bars. The arrangement direction of the multiple water equalizing bars is parallel to the arrangement direction of the multiple polymer films in the corresponding film group. A clamping space is formed between adjacent water equalizing bars. The clamping space corresponds one-to-one to the polymer film in the corresponding film group. The upper end of the polymer film is located in the corresponding clamping space. The water equalizing bar has multiple water equalizing holes.

[0009] Preferably, an adjustment plate is slidingly provided in the uniform distribution box, and the sliding direction of the adjustment plate is parallel to the plane of the bottom wall of the uniform distribution box. The adjustment plate abuts against the bottom wall of the uniform distribution box. Adjustment holes are opened on the adjustment plate, and the adjustment holes correspond one-to-one to the water holes. A floating plate is slidingly provided in the uniform distribution box, and the sliding direction of the floating plate is parallel to the depth direction of the uniform distribution box. The floating plate is located above the adjustment plate, and a pull rope is provided between the floating plate and the adjustment plate. An elastic member is provided between the bottom wall of the uniform distribution box and the adjustment plate. When the elastic member is in a natural state, the adjustment hole is misaligned with the corresponding water hole, and the pull rope is in a relaxed state.

[0010] Preferably, a circulating liquid pipeline is provided between the bottom and the top of the tank body, and the circulating liquid pipeline is used to transport the concentrated liquid at the bottom of the tank body to multiple evenly distributed boxes respectively. A circulating liquid pump body is installed on the circulating liquid pipeline, and the bottom of the tank body is connected to a concentrated liquid output pipe, and a concentrated liquid pump body is installed on the concentrated liquid output pipe. The concentrated liquid output pipe is used to connect with an external concentrated liquid cache tank.

[0011] Preferably, the air equalizing mechanism includes a plurality of air equalizing strips, each of which corresponds one-to-one to the polymer film in the corresponding film group, a steam inlet is provided on the side wall of the polymer film, the air equalizing strip is located in the steam inlet of the corresponding polymer film, adjacent air equalizing strips are abutted against each other by the polymer film to form an air inlet plane, and the air equalizing strip has a plurality of air equalizing holes.

[0012] Preferably, the condensate collection mechanism includes a condensate collecting pipe and a condensate box, the condensate collecting pipe is connected to a condensate branch pipe, the condensate collecting pipe is passed through the tank body, the condensate collecting pipe is connected to a condensate branch pipe, the condensate branch pipe is located inside the tank body and below the multiple groups of film groups, the lower ends of the multiple polymer films in the film group are all connected to the condensate branch pipe, the condensate box is located outside the tank body, and the condensate collecting pipe is connected to the condensate box.

[0013] Preferably, the falling film evaporation system further includes a second heat exchanger, the condensation tank is connected to the second heat exchanger, and the second heat exchanger is used to exchange heat between the condensate in the condensation tank and the feed liquid entering the liquid inlet pipe.

[0014] In a second aspect, the present application provides a falling film thin film evaporation process, which adopts the following technical solution: A falling film thin film evaporation process, using the falling film thin film evaporation system, comprises the following steps: Step 1: The external hot steam transported by the steam transport pipe is exchanged with the liquid entering the liquid inlet pipe through the first heat exchanger, and the liquid after heat exchange is input into the tank through the liquid inlet pipe; Step 2: The slurry then enters multiple uniform distribution boxes, and then flows through multiple water holes on the uniform distribution boxes to the water distribution strip below. The slurry flows evenly through the water distribution holes on the multiple water distribution strips to the outer walls of multiple polymer films; Step 3: The steam evaporated from the outer wall of the film is pressurized and heated by a steam compressor and transported to multiple gas equalization mechanisms. The steam then evenly enters multiple polymer films through the gas equalization mechanisms, and the steam in the polymer films exchanges heat with the liquid on the outer wall of the polymer film to evaporate; Step 4: The concentrated liquid is then obtained at the bottom wall of the tank body. The concentrated liquid at the bottom of the tank body enters the uniform distribution box again through the circulating liquid pump body and the circulating liquid pipeline for evaporation. The concentration of the concentrated liquid at the bottom of the tank body is detected by the concentration sensor at the bottom of the tank body. When the concentration detection value is greater than the preset value, the concentrated liquid is transported from the concentrated liquid output pipe to the external concentrated liquid buffer tank through the concentrated liquid pump body. By adding a reagent to the concentrated liquid buffer tank and then filtering the liquid in the concentrated liquid buffer tank, the solid and liquid are separated. The separated filter residue is collected separately and outsourced for treatment, and the separated filtrate is transported to the raw liquid storage tank and heat exchanged again before entering the tank body; Step 5: The condensate in the polymer film enters the condensation tank through the condensate manifold, and the condensate is heat-exchanged with the original liquid entering the liquid inlet pipe through the second heat exchanger.

[0015] In summary, this application has the following beneficial technical effects: The feed liquid enters the tank body through the liquid inlet pipe, and then flows to the outer wall of multiple groups of film groups. Under the action of gravity, the feed liquid naturally falls down along the surface of the film group to form a uniform liquid film. The steam evaporating from the outer wall of the film group is sucked into the steam compressor through the pipe for compression. The steam compressor pressurizes and heats the steam evaporated from the outer wall of the film group and transports it to multiple gas equalization mechanisms. The high-temperature steam is evenly transported to the corresponding film group through the gas equalization mechanism. At this time, the high-temperature steam in the film group exchanges heat with the feed liquid on the outer wall of the film group for evaporation, and the interior of the film group expands and presents an inflated form, which increases the surface area and the heat exchange area. In this way, concentrated liquid is obtained at the bottom of the tank body and condensate is obtained at the condensate collecting mechanism. The evaporated steam of the feed liquid enters the steam compressor for pressurization and temperature increase, and then the feed liquid itself is subjected to heat exchange and evaporation, thereby realizing effective utilization of the evaporated steam. There is no need to introduce a large amount of external high-temperature steam for heat exchange with the feed liquid, which saves costs to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present application.

[0017] Figure 2 It is a schematic diagram of the overall structure of the interior of the tank body in the embodiment of the present application.

[0018] Figure 3 It is an exploded diagram of the structure of the uniform distribution box and the water uniform distribution strip in the embodiment of the present application.

[0019] Figure 4 It is a cross-sectional view of the local structure of the polymer film in the embodiment of the present application.

[0020] Figure 5 It is a cross-sectional view of the overall structure of the uniform distribution box in the embodiment of the present application.

[0021] Figure 6 yes Figure 5 Enlarged view of part A.

[0022] Explanation of reference numerals: 1. tank; 2. water distribution mechanism; 201. distribution box; 202. water distribution strip; 3. film group; 31. polymer film; 4. steam compressor; 5. condensate collection mechanism; 51. condensate manifold; 52. condensate tank; 6. liquid inlet pipe; 8. concentrate outlet pipe; 9. first heat exchanger; 10. steam delivery pipe; 11. water hole; 12. water distribution hole; 13. adjustment plate; 14. adjustment hole; 15. floating plate; 16. pull rope; 17. distribution Gas strip; 18. Steam inlet; 19. Air equalization hole; 20. Second heat exchanger; 21. Circulating liquid pipeline; 22. Circulating liquid pump body; 23. Water channel; 231. Wave point water channel; 232. Wave water channel; 233. Straight water channel; 24. Water outlet; 25. Guide plate; 26. Telescopic rod; 27. Slide; 28. Slider; 29. Guide pulley; 30. Spring; 32. Micropore; 33. Connecting pipe; 34. Flange; 35. Water collector; 36. Condensate branch pipe. DETAILED DESCRIPTION

[0023] The following combination Figures 1-6 This application is described in further detail.

[0024] The embodiment of the present application discloses a falling film thin film evaporation system. Figure 1 and Figure 2 The falling film evaporation system includes a tank body 1, a film group 3, a steam compressor 4, an air equalization mechanism and a condensate collection mechanism 5. The cross section of the tank body 1 is rectangular. In other embodiments, the cross section of the tank body 1 can be a circle or other shapes. During operation, the tank body 1 is in a negative pressure state, and the pressure value is -1 kPa to -95 kPa. The material of the negative pressure tank body 1 is not limited to carbon steel, 304 stainless steel, 316L stainless steel, titanium, aluminum alloy and other materials.

[0025] Reference Figure 1 and Figure 2 The upper end of the tank body 1 is connected to a liquid inlet pipe 6 for feeding the feed liquid. The film groups 3 are all arranged in the tank body 1. There are multiple groups of film groups 3 distributed in the tank body 1. The feed liquid entering the liquid inlet pipe 6 is used to flow along the outer wall of the multiple groups of film groups 3.

[0026] Reference Figure 1 and Figure 2 The input end of the steam compressor 4 is connected to the top of the tank body 1 through a pipeline, so that the steam generated by the evaporation of the liquid is conveniently sucked into the steam compressor 4; the gas equalizing mechanism corresponds to the film group 3 one by one, and the gas equalizing mechanism is arranged in the corresponding film group 3. Each gas equalizing mechanism is connected to the output end of the steam compressor 4. The gas equalizing mechanism is used to evenly introduce the high-temperature steam output by the steam compressor 4 into the corresponding film group 3. The condensate collecting mechanism 5 is arranged on the tank body 1, and the condensate collecting mechanism 5 is used to collect the condensate in multiple groups of film groups 3.

[0027] During operation, the feed liquid is input into the upper end of the tank body 1 through the liquid inlet pipe 6, and then the feed liquid flows to the outer wall of the multiple film groups 3. Under the action of gravity, the feed liquid flows from top to bottom along the outer wall of the film group 3 to form a liquid film. In the initial state, external high-temperature steam is introduced into the tank body 1 to heat the feed liquid on the outer wall of the film group 3. The steam evaporated from the outer wall of the film group 3 is sucked into the steam compressor 4 through the pipeline for compression. The steam compressor 4 pressurizes and heats the steam evaporated from the outer wall of the film group 3 and transports it to each gas equalizing mechanism. Then the high-temperature steam is evenly transported to the corresponding film group 3 through the gas equalizing mechanism. At this time, the high-temperature steam in the film group 3 and the film group 3 The feed liquid on the outer wall is heat exchanged and evaporated. At this time, the input of external high-temperature steam can be reduced or stopped. The inside of the membrane group 3 expands and presents an inflated state, which increases the surface area and the heat exchange area. Under the negative pressure environment, the feed liquid will evaporate quickly, and the cycle is carried out to obtain concentrated liquid at the bottom of the tank body 1 and condensate at the condensate collecting mechanism 5. The present application utilizes the steam evaporated from the feed liquid to enter the steam compressor 4 for pressurization and temperature increase, and then heat exchange and evaporate the feed liquid itself, thereby achieving effective utilization of the evaporated steam. There is no need to introduce a large amount of external high-temperature steam for heat exchange with the feed liquid, which saves costs to a certain extent.

[0028] Specifically, when the feed liquid initially enters the tank body 1 for evaporation, external high-temperature steam can be introduced into the tank body 1 to heat the feed liquid on the outer wall of the film group 3. After the steam compressor 4 extracts the steam and pressurizes it into each film group 3, the input of external high-temperature steam can be reduced or stopped. Due to the heat exchange of the secondary compressed steam, the amount of external high-temperature steam can be greatly reduced, thereby achieving the effect of cost saving.

[0029] Reference Figure 2 and Figure 3 To facilitate sufficient heat exchange between the liquid feed and the high-temperature steam, multiple film groups 3 are arranged in two rows, each facing the other, to facilitate upward steam flow. Each film group 3 includes multiple polymer films 31, which are arranged in sequence along the horizontal direction within the tank body 1, with the arrangement direction of the multiple polymer films 31 parallel to the length of the tank body 1. Specifically, the polymer films 31 are rectangular or cubic in shape and are mounted below the water-distributing mechanism 2. The thickness of the polymer films 31 ranges from 0.01mm to 1mm, and the surface of the polymer films 31 is smooth and not prone to scabbing. The material of the polymer films 31 is resistant to high temperatures and corrosion, with a high thermal conductivity ratio. The material is not limited to one or more of PP, PE, PTFE, FEP, PEEK, PA, PS, graphite, silicon carbide, aluminum, silver, and titanium. Among them, PP refers to polypropylene material; PE refers to polyethylene material; PTFE refers to polytetrafluoroethylene material; FEP refers to fluorinated ethylene propylene copolymer material; PEEK refers to polyetheretherketone material; PA refers to polyamide material; PS refers to polystyrene material.

[0030] Reference Figure 3 and Figure 4 The inner wall of the polymer film 31 is provided with a water channel 23. The water channel 23 comprises a plurality of wavy water channels 231, a wave channel 232, and a straight water channel 233, which are formed sequentially by hot pressing from top to bottom. The wavy water channels 231 are multiple circular thermoplastic dots. One end of the straight water channel 233 is connected to the wavy water channel 232, and the other end is connected to the condensate collection mechanism 5. The polymer film 31 is formed by hot pressing in one piece, which helps to ensure the formation of the wavy water channels 231, the wave channel 232, and the straight water channels 233 within the film.

[0031] Since the high-temperature steam that has just entered the polymer film 31 is in a gaseous state, the high-temperature steam is easily gathered under the action of multiple wave-point water channels 231. The accumulated high-temperature steam falls and then flows along the wavy flow channel formed by multiple wave water channels 232 to the multiple straight water channels 233, and then enters the condensate collection mechanism 5 from the straight water channel 233, which can evenly cool and guide the high-temperature steam entering the polymer film 31, thereby helping to improve the evaporation effect.

[0032] Reference Figure 2 and Figure 3 In order to facilitate the uniform guidance of the liquid entering the liquid inlet pipe 6 to the outer walls of the multiple polymer films 31 in the corresponding film group 3, the evaporation system also includes a water distribution mechanism 2. The water distribution mechanism 2 is arranged in the tank body 1 and corresponds to the film group 3 one by one. The water distribution mechanism 2 is located above the corresponding film group 3. The setting of the water distribution mechanism 2 helps to uniformly guide the liquid entering the liquid inlet pipe 6 to the outer wall of the corresponding film group 3, so that the liquid flows from top to bottom in a film-like manner along the outer wall of the film group 3.

[0033] Reference Figure 2 and Figure 3 Specifically, the water distribution mechanism 2 includes a water distribution box 201 and a water distribution bar 202. The water distribution box 201 is fixedly arranged at the upper end of the tank body 1 and is located above the corresponding film group 3. Furthermore, the cross section of the water distribution box 201 is rectangular. The liquid inlet pipe 6 is fixedly inserted into the tank body 1 and is located between two rows of film groups 3. A first branch pipe (not shown in the figure) is distributed above the multiple water distribution boxes 201. Each first branch pipe is connected to the liquid inlet pipe 6, thereby facilitating the flow of the liquid in the liquid inlet pipe 6 to the multiple water distribution boxes 201. The first branch pipe is located above the corresponding water distribution box 201, so that the fluidity of the liquid in the water distribution box 201 and the vibration of the water distribution box 201 do not affect the water inlet pipe 6. The bottom wall of the water distribution box 201 is provided with multiple water holes 11 (refer to Figure 5 ).

[0034] Reference Figure 2 and Figure 3There are multiple water balancing strips 202 and they are located below the corresponding uniform distribution box 201. The arrangement direction of the multiple water balancing strips 202 is parallel to the arrangement direction of the multiple polymer films 31 in the corresponding film group 3. The length direction of the water balancing strips 202 is perpendicular to the arrangement direction of the multiple water balancing strips 202. The multiple water balancing strips 202 are fixed in the tank body 1 by multiple screws extruded in series. A clamping space is formed between adjacent water balancing strips 202 in the water balancing mechanism 2. The clamping space corresponds one-to-one to the polymer film 31. The upper end of the polymer film 31 is located in the corresponding clamping space. The adjacent water balancing strips 202 clamp and fix the upper end of the polymer film 31 therebetween. There are multiple water balancing holes 12 on the water balancing strip 202. The arrangement direction of the multiple water balancing holes 12 is parallel to the length direction of the corresponding water balancing strip 202.

[0035] Reference Figure 2 and Figure 3 , multiple water balancing strips 202 in the water balancing mechanism 2 are squeezed in sequence to form a water inlet surface, and the distribution box 201 covers the water inlet surface formed by the multiple water balancing strips 202. In the specific implementation process, a certain gap is left between the bottom wall of the distribution box 201 and the upper surface of the multiple water balancing strips 202, and a rectangular frame is fixed between them. The rectangular frame seals the gap between the distribution box 201 and the corresponding multiple water balancing strips 202, so that the liquid will not flow to other positions in the tank body 1.

[0036] When the liquid in the liquid inlet pipe 6 enters the uniform distribution box 201 through the first branch pipe, the liquid in the uniform distribution box 201 flows evenly through multiple water holes 11 to the inlet water surface formed by the multiple water balancing strips 202 below, and then the liquid flows through the water balancing holes 12 on the multiple water balancing strips 202 to the corresponding polymer film 31, thereby helping the liquid to flow evenly from top to bottom along the outer walls of the multiple polymer films 31 to form a liquid film for evaporation, which helps to improve the evaporation effect of the liquid.

[0037] Reference Figure 3 and Figure 4Water-distributing strip 202 is made of inorganic or organic materials, including but not limited to PP, PE, PS, PA, PSE, PTFE, iron, stainless steel, aluminum, titanium, gold, silver, fiberglass, graphite, and silicon carbide. It offers advantages such as excellent corrosion resistance, low cost, readily available materials, and high practicality. Furthermore, water-distributing strip 202 can be composed of two half strips joined by male and female buckles, or it can be a complete rectangular strip. In this embodiment of the present application, the form of water-distributing strip 202 is not limited. When the water-distributing strip 202 is in the form of two water-distributing half-strips, a plurality of mutually abutting separators are integrally formed on the mutually adjacent sides of the two water-distributing half-strips, and a plurality of water-distributing holes 12 are formed by abutting each other between the separators. The water-distributing half-strips can also be formed by splicing a plurality of strips. This form of water-distributing strip 202 is easy to assemble and disassemble and can be spliced as needed. When the water-distributing strip 202 is in the form of a complete rectangular strip, a plurality of water-distributing holes 12 are formed by opening a plurality of holes on the rectangular strip. This form of water-distributing strip 202 does not require splicing and is easy to install.

[0038] Reference Figure 1 、 Figure 2 and Figure 3 To facilitate the uniform introduction of the high-temperature steam output by the steam compressor 4 into the multiple polymer films 31, the gas equalization mechanism includes multiple gas equalization strips 17. Each gas equalization strip 17 corresponds to a polymer film 31 in a corresponding film group 3. Steam inlets 18 are provided on the sidewalls of the polymer films 31. The gas equalization strips 17 are installed within the steam inlets 18 of the corresponding polymer films 31. The gas equalization strips 17 extend vertically, and adjacent gas equalization strips 17 abut against each other across the polymer films 31 to form an air intake plane. A flange 34 is fixed to the air intake plane, covering the air intake plane to form a sealed space. The output end of the steam compressor 4 is connected to a connecting pipe 33. The connecting pipe 33 extends between the two rows of film groups 3 in the tank body 1. The air intake planes of the two film groups 3 are located on the side close to each other. The flange 34 of each film group 3 is connected to the connecting pipe 33. To facilitate the installation of the air equalizing strips 17, multiple air equalizing strips 17 are fixed in the tank body 1 by multiple screws, and adjacent air equalizing strips 17 are pressed against each other; there are multiple air equalizing holes 19 on the air equalizing strips 17, and the arrangement direction of the multiple air equalizing holes 19 is parallel to the length direction of the air equalizing strips 17.

[0039] During use, the high-temperature steam output by the steam compressor 4 enters the multiple flanges 34 through the connecting pipes 33, and then evenly enters each polymer film 31 along the gas distribution holes 19 on the multiple gas distribution strips 17 to ensure the evaporation effect.

[0040] Reference Figure 3 and Figure 4The air distribution strip 17 is made of inorganic or organic materials, including but not limited to PP, PE, PS, PA, PSE, PTFE, iron, stainless steel, aluminum, titanium, gold, silver, fiberglass, graphite, and silicon carbide. It has the advantages of good corrosion resistance, low cost, readily available materials, and high practicality. Furthermore, the air distribution strip 17 can be composed of two half air distribution strips joined by male and female buckles, or it can be a complete rectangular strip. In the present embodiment, the form of the air distribution strip 17 is not limited. When the air equalizing strip 17 is in the form of two air equalizing half strips, a plurality of abutting pieces are integrally formed on the sides of the two air equalizing half strips that are close to each other, and a plurality of air equalizing holes 19 are formed by abutting each other in pairs of the abutting pieces. The air equalizing half strips can be made by splicing a plurality of strips. This form of air equalizing strip 17 is easy to assemble and disassemble and can be spliced as needed. When the air equalizing strip 17 is in the form of a complete rectangular strip, a plurality of air equalizing holes 19 are formed by opening a plurality of holes on the rectangular strip. This form of air equalizing strip 17 does not require splicing and is easy to install.

[0041] Reference Figure 1 and Figure 2 In order to facilitate the collection of the condensate, the condensate collection mechanism 5 includes a condensate collection pipe 51 and a condensate box 52. The condensate collection pipe 51 is fixedly installed on the tank body 1. The condensate collection pipe 51 is connected to the condensate branch pipe 36. There are two condensate branch pipes 36. The two condensate branch pipes 36 are respectively located under two rows of multiple film groups 3. The condensate box 52 is located outside the tank body 1. The condensate collection pipe 51 is connected to the condensate box 52. A vacuum generator is installed on the condensate box 52. The vacuum generator is connected to the inside of the tank body 1, so as to facilitate the realization of a negative pressure state inside the tank body 1.

[0042] Reference Figure 2 and Figure 4 , a water outlet hole 24 is opened on the side wall of the lower end of each polymer film 31, and a guide plate 25 is fixedly set on the inner side wall of the lower end of each polymer film 31. The guide plate 25 is aligned with the water outlet hole 24 in the corresponding polymer film 31 and is connected with the water outlet hole 24. The axial direction of the guide plate 25 is parallel to the arrangement direction of the multiple polymer films 31. The guide plates 25 in the multiple polymer films 31 are pressed together to form an internal horizontal sealed channel to facilitate the flow of condensed water; specifically, a plurality of flow channels for draining the condensate are provided on the guide plate 25, and the end of each straight water channel 233 away from the wavy water channel 232 is connected with the flow channel on the guide plate 25, so that the condensate in the polymer film 31 can enter the water outlet hole 24 through the flow channel on the guide plate 25.

[0043] Reference Figure 1 and Figure 4, a water collector 35 is distributed under the multiple polymer films 31 of each film group 3, and the water collector 35 includes an abutment ring and a connecting pipe. The abutment ring is annular, and the axial direction of the connecting pipe is perpendicular to the axial direction of the abutment ring, and the connecting pipe is connected to the inside of the abutment ring, and the abutment ring is clamped between the guide plates 25 in any adjacent two polymer films 31 in the film group 3. Optimally, the abutment ring is clamped between the guide plates 25 in the two middle polymer films 31 in the film group 3 to facilitate uniform discharge of the condensate; the axial direction of the abutment ring is parallel to the axial direction of the multiple guide plates 25, so that the multiple guide plates 25 can be connected to the water collector 35. Specifically, the multiple guide plates 25 and the abutment ring can be connected and fixed in series by screws; the end of the connecting pipe away from the abutment ring is connected with the condensate branch pipe 36 below, so as to facilitate the transportation of the condensate to the condensate box 52 through the condensate branch pipe 36 and the condensate collecting pipe 51. The guide plate 25 is not limited to one or a combination of PP, PE, PTFE, FEP, PEEK, PA, PS, graphite, silicon carbide, aluminum, silver, and titanium. The configuration of the guide plate 25 facilitates the flow of the condensate in the polymer film 31 to the condensate manifold 51.

[0044] The high-temperature steam in the polymer film 31 exchanges heat with the liquid on the outer surface of the polymer film 31, so that the high-temperature steam in the polymer film 31 is condensed into condensate. The condensate then enters the water collector 35 from the guide plate 25 along the water channel 23, and then enters the condensate branch pipe 36 and the condensate collecting pipe 51 from the corresponding water collector 35, and then enters the condensate box 52 from the condensate collecting pipe 51.

[0045] Reference Figure 1 and Figure 2 To fully utilize the temperature of the condensate, the falling-film evaporation system also includes a second heat exchanger 20. The condensate tank 52 is connected to the second heat exchanger 20 via a pipeline. The input end of the second heat exchanger 20 is connected to a first raw liquid inlet pipe for communication with the raw liquid storage tank, and the output end of the second heat exchanger 20 is connected to the liquid inlet pipe 6. The second heat exchanger 20 exchanges heat with the liquid entering the liquid inlet pipe 6, thereby utilizing the waste heat of the condensate to heat the liquid entering the liquid inlet pipe 6 and reducing costs.

[0046] Reference Figure 1 and Figure 2In order to facilitate sufficient heating of the incoming liquid, the falling film evaporation system also includes a first heat exchanger 9, a second heat exchanger 20 is connected in parallel with the first heat exchanger 9, and the first heat exchanger 9 is connected to a steam delivery pipe 10 for delivering external high-temperature steam. The input end of the first heat exchanger 9 is connected to a second raw liquid inlet pipe for communication with the raw liquid storage tank, and the output end of the first heat exchanger 9 is connected to the liquid inlet pipe 6, so that the external high-temperature steam delivered from the steam delivery pipe 10 passes through the first heat exchanger 9 to exchange heat with the liquid entering the liquid inlet pipe 6, thereby ensuring that the liquid can evaporate quickly after entering the tank body 1. During use, the first heat exchanger 9 is activated for steam heat exchange only when the temperature of the raw liquid entering the tank body 1 does not reach the evaporation temperature. In other embodiments, in order to ensure that the liquid on the outer wall of the polymer film 31 is fully heated, the steam delivery pipe 10 can also be directly connected to the interior of the tank body 1.

[0047] Reference Figure 1 and Figure 2 Specifically, both the first heat exchanger 9 and the second heat exchanger 20 are plate-type heat exchangers. The raw liquid of the feed is stored in a raw liquid storage tank. After being filtered by a filter press, the raw liquid is pumped into the first raw liquid inlet pipe and the second raw liquid inlet pipe, respectively, to facilitate heat exchange through the first heat exchanger 9 and the second heat exchanger 20.

[0048] Reference Figure 1 and Figure 2 To achieve a closed-loop system, a concentration sensor (not shown) is installed at the bottom of tank 1 to detect the concentration of the concentrate. This sensor is wirelessly connected to an external control platform to transmit the concentration value. A concentrate output pipe 8 is connected to the bottom of tank 1, and a concentrate pump is installed on this pipe. This pipe connects to an external concentrate buffer tank. By adding reagents to the concentrate buffer tank and filtering the liquid within, the solid and liquid are separated. The separated filter residue is collected separately and outsourced for processing. The separated filtrate is then transported to the raw liquid storage tank, where it undergoes heat exchange again before entering tank 1 to ensure evaporation.

[0049] When the concentration detection value received by the external control platform is less than the preset value, the concentrate pump body is closed; when the concentration detection value received by the external control platform is greater than the preset value, the concentrate at the bottom of the tank body 1 is pumped into the concentrate output pipe 8 through the concentrate pump body and discharged from the tank body 1, and then enters the concentrate buffer tank for subsequent processing.

[0050] Reference Figure 1 and Figure 2A circulating liquid pipe 21 is provided between the bottom and top of the tank body 1. One end of the circulating liquid pipe 21 is connected to the bottom of the tank body 1, and the other end extends into the tank body 1 between the two rows of film groups 3. A second branch pipe (not shown) is arranged above each uniform distribution box 201. Each second branch pipe is connected to the circulating liquid pipe 21, so that the circulating liquid pipe 21 can transport the concentrated liquid at the bottom of the tank body 1 to the multiple uniform distribution boxes 201. A circulating liquid pump body 22 is installed on the circulating liquid pipe 21. The concentrated liquid at the bottom of the tank body 1 is pumped into the circulating liquid pipe 21 by the circulating liquid pump body 22 and then enters the uniform distribution box 201 for evaporation and concentration, thereby forming a high-concentration concentrated liquid at the bottom of the tank body 1, which helps to ensure the concentration effect.

[0051] Reference Figure 3 and Figure 5 An adjustment plate 13 is slidingly provided in the uniform distribution box 201, and the sliding direction of the adjustment plate 13 is parallel to the plane of the bottom wall of the uniform distribution box 201. Specifically, the sliding direction of the adjustment plate 13 is parallel to the arrangement direction of the multiple polymer films 31 in the film group 3. The adjustment plate 13 is in contact with the bottom wall of the uniform distribution box 201, and multiple telescopic rods 26 are fixed between the adjustment plate 13 and the side wall of the uniform distribution box 201. The length direction of the telescopic rods 26 is parallel to the sliding direction of the adjustment plate 13; an adjustment hole 14 is provided on the adjustment plate 13, and the adjustment hole 14 corresponds one-to-one to the water hole 11, and a slide groove 27 is provided on the inner wall of the uniform distribution box 201.

[0052] Reference Figure 5 and Figure 6 A slider 28 is slidingly provided in the slide groove 27. The sliding direction of the slider 28 is parallel to the depth direction of the uniform distribution box 201. The cross-section of the slider 28 and the slide groove 27 is T-shaped, so that the slider 28 will not be separated from the slide groove 27. The inner wall of the lower end of the slide groove 27 is located above the adjustment plate 13. Specifically, the height of the inner wall of the lower end of the slide groove 27 is set as needed.

[0053] Reference Figure 5 and Figure 6 A floating plate 15 is fixed on the slider 28, so that the floating plate 15 and the uniform distribution box 201 can slide relative to each other. The sliding direction of the floating plate 15 is parallel to the depth direction of the uniform distribution box 201. The floating plate 15 is located above the adjusting plate 13. A pull rope 16 is fixed between the floating plate 15 and the adjusting plate 13. In order to facilitate the guidance of the pull rope 16, a guide pulley 29 is fixedly installed on the inner wall of the uniform distribution box 201 on the side close to the floating plate 15. The guide pulley 29 is located below the floating plate 15, and the pull rope 16 between the adjusting plate 13 and the floating plate 15 slides and overlaps on the guide pulley 29.

[0054] Reference Figure 5 and Figure 6An elastic member is provided between the bottom wall of the uniform distribution box 201 and the adjustment plate 13. When the elastic member is in a natural state, the adjustment hole 14 is misaligned with the corresponding water hole 11, and the pull rope 16 is in a relaxed state. Specifically, the elastic member includes a spring 30. The extension direction of the spring 30 is parallel to the sliding direction of the adjustment plate 13. One end of the spring 30 is fixed on the inner wall of the uniform distribution box 201 close to the float plate 15, and the other end is fixed on the adjustment plate 13. The pull rope 16 is located in the spring 30. The buoyancy of the float plate 15 is greater than the sum of the friction between the adjustment plate 13 and the bottom wall of the uniform distribution box 201 and the elastic force of the spring 30.

[0055] Reference Figure 5 and Figure 6 In order to ensure that when the floating plate 15 is at the bottom and the regulating plate 13 closes the water hole 11, the remaining liquid in the uniform distribution box 201 can flow out, microholes 32 are opened on the bottom wall at both ends of the uniform distribution box 201, and the regulating plate 13 is located between the two microholes 32. The cross-section of the microhole 32 is much smaller than the cross-section of the water hole 11, and the regulating plate 13 is always misaligned with the microholes 32 at both ends.

[0056] When the liquid in the liquid inlet pipe 6 initially enters the uniform distribution box 201, at this time, the spring 30 is in a natural state, the regulating plate 13 closes the water hole 11, and only a very small amount of the liquid in the uniform distribution box 201 can flow out through the micropores 32. As the liquid gradually increases, the liquid level in the uniform distribution box 201 rises. When the liquid level rises to contact the bottom wall of the float plate 15, as the liquid level continues to rise, the liquid will drive the float plate 15 to rise. In the process of the float plate 15 moving upward, the regulating plate 13 is pulled by the pull rope 16 to slide the compression spring 30 in the direction close to the float plate 15, gradually aligning the regulating hole 14 with the corresponding water hole 11. At this time, the liquid in the uniform distribution box 201 can quickly pass through multiple water holes 11 at the same time and flow to the water balancing bar 202 below, which helps to solve the problem that when the liquid just enters the uniform distribution box 201 or the amount of liquid inflow is small, the liquid only flows out quickly from some water holes 11 on the bottom wall of the uniform distribution box 201, resulting in uneven evaporation.

[0057] The implementation principle of the embodiment of the present application is as follows: when working, the external high-temperature steam transported by the steam delivery pipe 10 is exchanged with the feed liquid entering the liquid inlet pipe 6 through the first heat exchanger 9, and the feed liquid after heat exchange is input into the tank body 1 through the liquid inlet pipe 6, and then the feed liquid flows into each uniform distribution box 201 through the first branch pipe. At this time, the spring 30 is in a natural state, and the regulating plate 13 closes the water hole 11. Only a very small part of the feed liquid entering the uniform distribution box 201 can flow out through the micropores 32. As the feed liquid gradually increases, the liquid level in the uniform distribution box 201 rises. When the liquid level rises to contact the bottom wall of the float plate 15, as the liquid level continues to rise, the feed liquid will drive the float plate 15 to rise. In the process of the float plate 15 moving upward, the regulating plate 13 is pulled by the pull rope 16 to slide toward the direction close to the float plate 15, and then the regulating hole 14 is gradually aligned with the corresponding water holes 11. At this time, the liquid in the uniform distribution box 201 can quickly and simultaneously pass through multiple water holes 11 and evenly flow to the water uniforming bar 202 below. Then the liquid flows evenly to the outer walls of multiple polymer films 31 through the water uniforming holes 12 on the multiple water uniforming bars 202. In the initial state, external high-temperature steam can also be directly introduced into the tank body 1 to heat and evaporate the liquid. The steam compressor 4 pressurizes and heats the steam evaporated from the outer wall of the film and transports it to multiple air inlet planes through the connecting pipe 33. Then the high-temperature steam evenly enters the multiple polymer films 31 through the air uniforming holes 19 on the multiple air uniforming bars 17. The high-temperature steam in the polymer film 31 exchanges heat and evaporates with the liquid on the outer wall of the polymer film 31. Then the introduction of external high-temperature steam into the tank body 1 can be reduced or stopped.

[0058] Then, the concentrated liquid is obtained from the bottom wall of the tank body 1, and the concentration of the concentrated liquid at the bottom of the tank body 1 is detected by the conductivity sensor or turbidity sensor at the bottom of the tank body 1. When the concentration detection value is less than the preset value, the concentrated liquid at the bottom of the tank body 1 enters the uniform distribution box 201 again through the circulating liquid pump body 22 and the circulating liquid pipeline 21 for evaporation. When the concentration detection value is greater than the preset value, the concentrated liquid is transported from the concentrated liquid output pipe 8 to the external concentrated liquid buffer tank for subsequent processing through the concentrated liquid pump body; the condensate in the polymer film 31 is collected in the condensate collection pipe 51 through the water channel 23, the guide plate 25 and the water collector 35, and then the condensate enters the condensation Box 52, through the second heat exchanger 20, the condensate is exchanged with the raw liquid entering the liquid inlet pipe 6; so that the steam delivery pipe 10 only needs to transport a small amount of external high-temperature steam to the first heat exchanger 9 to exchange heat with the raw liquid entering the liquid inlet pipe 6, so that the evaporation cycle can be carried out. The present application utilizes the steam evaporated from the feed liquid to pressurize and heat it in the steam compressor 4, and then heat-exchange and evaporate the feed liquid itself, while utilizing the waste heat of the condensate to exchange heat with the feed liquid entering the liquid inlet pipe 6, thereby realizing the effective utilization of the condensate and secondary compressed steam, helping to reduce the amount of external high-temperature steam introduced, and saving costs to a certain extent.

[0059] The present application also discloses a falling film thin film evaporation process. The falling film thin film evaporation process uses the above-mentioned falling film thin film evaporation system and includes the following steps: Step 1: The external high-temperature steam delivered by the steam delivery pipe 10 is heat exchanged with the liquid entering the liquid inlet pipe 6 through the first heat exchanger 9, and the liquid after heat exchange is input into the tank body 1 through the liquid inlet pipe 6; Step 2: The slurry then enters the multiple uniform distribution boxes 201, and then flows through the multiple water holes 11 on the uniform distribution boxes 201 to the water distribution strips 202 below. The slurry then flows evenly through the multiple water distribution holes 12 on the water distribution strips 202 to the outer walls of the multiple polymer films 31. Step 3: The steam evaporated from the outer wall of the film is pressurized and heated by the steam compressor 4 and transported to multiple gas equalization mechanisms. Then, the high-temperature steam is uniformly introduced into the multiple polymer films 31 through the gas equalization mechanisms. The high-temperature steam in the polymer films 31 exchanges heat with the liquid on the outer wall of the polymer films 31 and evaporates. Step 4: Then, the concentrated liquid is obtained at the bottom wall of the tank body 1. The concentrated liquid at the bottom of the tank body 1 enters the uniform distribution box 201 again through the circulating liquid pump body 22 and the circulating liquid pipeline 21 for evaporation. The concentration of the concentrated liquid at the bottom of the tank body 1 is detected by the concentration sensor at the bottom of the tank body 1. When the concentration detection value is greater than the preset value, the concentrated liquid is transported from the concentrated liquid output pipe 8 to the external concentrated liquid buffer tank through the concentrated liquid pump body. By adding a reagent to the concentrated liquid buffer tank and then filtering the liquid in the concentrated liquid buffer tank, the solid and liquid are separated. The separated filter residue is separately collected and outsourced for processing, and the separated filtrate is transported to the raw liquid storage tank and heat exchanged again before entering the tank body 1. Step 5: The condensate in the polymer film 31 enters the condensate tank 52 through the condensate manifold 51 , and is heat-exchanged with the raw liquid entering the liquid inlet pipe 6 through the second heat exchanger 20 .

[0060] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A falling film thin film evaporation system, characterized in that: The invention comprises a tank body (1), a film group (3), a steam compressor (4), an air equalization mechanism and a condensate collecting mechanism (5), wherein the film group (3) is arranged in a plurality of groups in the tank body (1), the tank body (1) is connected with a liquid inlet pipe (6) for feeding liquid, the input end of the steam compressor (4) is connected with the tank body (1), the air equalization mechanism corresponds to the film group (3) one by one, the air equalization mechanism is arranged in the corresponding film group (3), each of the air equalization mechanisms is connected with the output end of the steam compressor (4), the air equalization mechanism is used to uniformly introduce the steam output by the steam compressor (4) into the corresponding film group (3), the condensate collecting mechanism (5) is arranged on the tank body (1), and the condensate collecting mechanism (5) is used to collect condensate in the plurality of film groups (3).

2. The falling film evaporation system according to claim 1, characterized in that: The falling film evaporation system further comprises a first heat exchanger (9), the first heat exchanger (9) being connected to a steam delivery pipe (10) for delivering external steam, and the first heat exchanger (9) being used to exchange heat between the steam delivered by the steam delivery pipe (10) and the feed liquid entering the liquid inlet pipe (6).

3. The falling film evaporation system according to claim 2, characterized in that: The plurality of film groups (3) are arranged in two rows and are opposite to each other. Each of the film groups (3) comprises a plurality of polymer films (31) sequentially arranged in the tank body (1) along a horizontal direction.

4. The falling film evaporation system according to claim 3, characterized in that: The evaporation system further comprises a water distribution mechanism (2), wherein the water distribution mechanism (2) corresponds to each of the film groups (3) on a one-to-one basis, and the water distribution mechanism (2) is located above the corresponding film group (3). The water distribution mechanism (2) is used to evenly guide the liquid entering through the liquid inlet pipe (6) to the outer wall of the corresponding film group (3); The water equalization mechanism (2) includes a water equalization box (201) and a water equalization bar (202) arranged in the tank body (1). The liquid in the liquid inlet pipe (6) flows into multiple water equalization boxes (201) respectively. The bottom wall of the water equalization box (201) is provided with multiple water holes (11). The water equalization box (201) is located above the water equalization bar (202). There are multiple water equalization bars (202). The arrangement direction of the multiple water equalization bars (202) is parallel to the arrangement direction of the multiple polymer films (31) in the corresponding film group (3). A clamping space is formed between adjacent water equalization bars (202). The clamping space corresponds to the polymer film (31) in the corresponding film group (3). The upper end of the polymer film (31) is located in the corresponding clamping space. The water equalization bar (202) has multiple water equalization holes (12).

5. The falling film evaporation system according to claim 4, characterized in that: An adjusting plate (13) is slidably provided in the uniform distribution box (201), the sliding direction of the adjusting plate (13) is parallel to the plane of the bottom wall of the uniform distribution box (201), the adjusting plate (13) is in contact with the bottom wall of the uniform distribution box (201), an adjusting hole (14) is provided on the adjusting plate (13), the adjusting hole (14) corresponds to the water hole (11) one by one, a floating plate (15) is slidably provided in the uniform distribution box (201), the floating plate (15) 5) has a sliding direction parallel to the depth direction of the uniform distribution box (201), the floating plate (15) is located above the adjustment plate (13), a pull rope (16) is provided between the floating plate (15) and the adjustment plate (13), an elastic member is provided between the bottom wall of the uniform distribution box (201) and the adjustment plate (13), when the elastic member is in a natural state, the adjustment hole (14) and the corresponding water hole (11) are misaligned, and the pull rope (16) is in a relaxed state.

6. The falling film evaporation system according to claim 4, characterized in that: A circulating liquid pipeline (21) is provided between the bottom of the tank body (1) and the top of the tank body (1), and the circulating liquid pipeline (21) is used to transport the concentrated liquid at the bottom of the tank body (1) to a plurality of uniform distribution boxes (201) respectively. A circulating liquid pump body (22) is installed on the circulating liquid pipeline (21). The bottom of the tank body (1) is connected to a concentrated liquid output pipe (8), and a concentrated liquid pump body is installed on the concentrated liquid output pipe (8). The concentrated liquid output pipe (8) is used to communicate with an external concentrated liquid buffer tank.

7. The falling film evaporation system according to claim 3, characterized in that: The gas equalizing mechanism includes a plurality of gas equalizing strips (17), each of the gas equalizing strips (17) corresponding to a polymer film (31) in a corresponding film group (3), a steam inlet (18) being provided on a side wall of the polymer film (31), the gas equalizing strips (17) being located in the steam inlet (18) of the corresponding polymer film (31), adjacent gas equalizing strips (17) being abutted against each other across the polymer film (31) to form an air inlet plane, and the gas equalizing strips (17) having a plurality of gas equalizing holes (19).

8. The falling film evaporation system according to claim 6, characterized in that: The condensate collecting mechanism (5) comprises a condensate collecting pipe (51) and a condensate box (52). The condensate collecting pipe (51) is provided on the tank body (1). The condensate collecting pipe (51) is connected to a condensate branch pipe (36). The condensate branch pipe (36) is located inside the tank body (1) and below the multiple film groups (3). The lower ends of the multiple polymer films (31) in the film groups (3) are all connected to the condensate branch pipe (36). The condensate box (52) is located outside the tank body (1). The condensate collecting pipe (51) is connected to the condensate box (52).

9. The falling film evaporation system according to claim 8, characterized in that: The falling film evaporation system further comprises a second heat exchanger (20), the condensation tank (52) being connected to the second heat exchanger (20), and the second heat exchanger (20) being used for exchanging heat between the condensate in the condensation tank (52) and the feed liquid entering the liquid inlet pipe (6).

10. A falling film thin film evaporation process, using the falling film thin film evaporation system according to claim 9, characterized in that: The steps include: Step 1: The external hot steam delivered by the steam delivery pipe (10) is heat-exchanged with the liquid entering the liquid inlet pipe (6) through the first heat exchanger (9), and the liquid after heat exchange is input into the tank body (1) through the liquid inlet pipe (6); Step 2: The feed liquid then enters the multiple uniform distribution boxes (201) respectively, and then flows to the water distribution strip (202) below through the multiple water holes (11) on the uniform distribution boxes (201). The feed liquid flows evenly to the outer walls of the multiple polymer films (31) through the multiple water distribution holes (12) on the multiple water distribution strips (202); Step 3: The steam evaporated from the outer wall of the film is pressurized and heated by the steam compressor (4) and transported to multiple gas equalization mechanisms. Then, the steam is uniformly introduced into the multiple polymer films (31) through the gas equalization mechanisms. The steam in the polymer film (31) exchanges heat with the liquid on the outer wall of the polymer film (31) and evaporates. Step 4: Then, a concentrated liquid is obtained on the bottom wall of the tank body (1). The concentrated liquid at the bottom of the tank body (1) enters the uniform distribution box (201) again through the circulating liquid pump body (22) and the circulating liquid pipeline (21) for evaporation. The concentration of the concentrated liquid at the bottom of the tank body (1) is detected by the concentration sensor at the bottom of the tank body (1). When the concentration detection value is greater than the preset value, the concentrated liquid is transported from the concentrated liquid output pipe (8) to the external concentrated liquid buffer tank through the concentrated liquid pump body. By adding a reagent to the concentrated liquid buffer tank and then filtering the liquid in the concentrated liquid buffer tank, the solid and liquid are separated. The separated filter residue is separately collected and outsourced for treatment, and the separated filtrate is transported to the raw liquid storage tank and heat exchanged again before entering the tank body (1). Step 5: The condensate in the polymer film (31) enters the condensation tank (52) through the condensate manifold (51), and the condensate is heat-exchanged with the original liquid entering the liquid inlet pipe (6) through the second heat exchanger (20).

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