Falling film thin film evaporation system and evaporation process

Abstract

This application relates to a falling film thin-film evaporation system and evaporation process, belonging to the field of falling film evaporation technology. The falling film thin-film evaporation system includes a tank, thin film groups, a steam compressor, a gas equalization mechanism, and a condensate collection mechanism. Multiple thin film groups are arranged within the tank. An inlet pipe for feeding liquid is connected to the tank. The input end of the steam compressor is connected to the tank. Each gas equalization mechanism corresponds to one thin film group and is located within that group. Each gas equalization mechanism is connected to the output end of the steam compressor. The gas equalization mechanism is used to uniformly introduce the steam output from the steam compressor into the corresponding thin film group. The condensate collection mechanism is located on the tank and is used to collect the condensate from multiple thin film groups. This application has a certain degree of cost-saving effect.

Description

Technical Field

[0001] This application relates to the field of falling film evaporation technology, and in particular to a falling film thin-film evaporation system and evaporation process. Background Technology

[0002] A falling film evaporator is an evaporation device used in industrial, chemical, and domestic fields to treat wastewater. Its working principle is mainly as follows: the feed liquid is added from the top of the falling film evaporator and distributed into the pipeline by the liquid distributor, so that the feed liquid forms a film and flows from top to bottom along the pipeline. High-temperature water vapor is introduced into the device to exchange heat with the feed liquid in the pipeline, so that the feed liquid in the pipeline evaporates and concentrates in this process. Finally, concentrated liquid and steam are obtained at the bottom of the device. Then, the steam and concentrated liquid are separated by a separator to obtain concentrated liquid and steam respectively.

[0003] Currently, falling film evaporators typically require a large amount of external high-temperature steam to be introduced over a long period of time to evaporate the liquid in the pipes, which is costly. Summary of the Invention

[0004] To save costs to a certain extent, this application provides a falling film thin-film evaporation system and evaporation process.

[0005] Firstly, this 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, thin film assemblies, a steam compressor, a gas equalization mechanism, and a condensate collection mechanism. Multiple thin film assemblies are arranged within the tank. An inlet pipe for feeding liquid is connected to the tank. The input end of the steam compressor is connected to the tank. Each gas equalization mechanism corresponds to one thin film assembly and is located within its respective assembly. Each gas equalization mechanism is connected to the output end of the steam compressor and is used to uniformly introduce steam output from the steam compressor into its corresponding thin film assembly. The condensate collection mechanism is located on the tank and is used to collect condensate from multiple thin film assemblies.

[0006] Preferably, the falling film thin-film evaporation system further includes a first heat exchanger, which is connected to a steam delivery pipe for conveying external steam. The first heat exchanger is used to exchange heat between the steam delivered by the steam delivery pipe and the liquid entering the inlet pipe.

[0007] Preferably, the multiple groups of the film are arranged in two rows and opposite each other, and each group of the film includes multiple polymer films arranged sequentially in the horizontal direction inside the tank.

[0008] Preferably, the evaporation system further includes a water equalization mechanism, which corresponds one-to-one with the film group and is located above the corresponding film group. The water equalization mechanism is used to uniformly guide the liquid entering from the inlet pipe to the outer wall of the corresponding film group. The water distribution mechanism includes a distribution box and a water distribution strip disposed inside the tank. The liquid in the inlet pipe flows into multiple distribution boxes. Multiple water passage holes are opened on the bottom wall of the distribution box. The distribution box is located above the water distribution strip. Multiple water distribution strips are provided. The arrangement direction of the multiple water distribution strips is parallel to the arrangement direction of multiple polymer films in the corresponding film group. A clamping space is formed between adjacent water distribution strips. The clamping space corresponds one-to-one with the polymer film in the corresponding film group. The upper end of the polymer film is located in the corresponding clamping space. The water distribution strip has multiple water distribution holes.

[0009] Preferably, an adjusting plate is slidably disposed inside the distribution box. The sliding direction of the adjusting plate is parallel to the plane of the bottom wall of the distribution box. The adjusting plate abuts against the bottom wall of the distribution box. An adjusting hole is provided on the adjusting plate, and the adjusting hole corresponds one-to-one with the water passage hole. A float plate is slidably disposed inside the distribution box. The sliding direction of the float plate is parallel to the depth direction of the distribution box. The float plate is located above the adjusting plate. A pull rope is disposed between the float plate and the adjusting plate. An elastic element is disposed between the bottom wall of the distribution box and the adjusting plate. When the elastic element is in its natural state, the adjusting hole and the corresponding water passage hole are misaligned, and the pull rope is in a slack state.

[0010] Preferably, a circulating liquid pipeline is provided between the bottom and top of the tank body. The circulating liquid pipeline is used to transport the concentrate at the bottom of the tank body to multiple uniform distribution boxes. A circulating liquid pump body is installed on the circulating liquid pipeline. A concentrate output pipe is connected to the bottom of the tank body. A concentrate pump body is installed on the concentrate output pipe. The concentrate output pipe is used to connect to an external concentrate buffer tank.

[0011] Preferably, the gas equalization mechanism includes multiple gas equalization strips, each corresponding to a polymer film in a corresponding film group. The sidewall of the polymer film is provided with a steam inlet, and the gas equalization strip is located inside the steam inlet of the corresponding polymer film. Adjacent gas equalization strips are separated by polymer films to form an air inlet plane, and the gas equalization strip has multiple gas equalization holes.

[0012] Preferably, the condensate collection mechanism includes a condensate manifold and a condensate box. The condensate manifold is connected to a condensate branch pipe and is installed on the tank body. The condensate manifold is connected to the condensate branch pipe, which is located inside the tank body and below multiple sets of film groups. The lower ends of multiple polymer films in the film groups are connected to the condensate branch pipe. The condensate box is located outside the tank body, and the condensate manifold is connected to the condensate box.

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

[0014] Secondly, this application provides a falling film thin-film evaporation process, which adopts the following technical solution: A falling film thin-film evaporation process, using the aforementioned falling film thin-film evaporation system, includes the following steps: Step 1: The external hot steam delivered by the steam delivery pipe is exchanged with the liquid entering the liquid inlet pipe through the first heat exchanger. The liquid after heat exchange is then fed into the tank through the liquid inlet pipe. Step 2: Next, the liquid enters multiple distribution boxes and flows through multiple water holes on the distribution boxes to the water distribution strips below. The liquid then flows evenly through the water distribution holes on the water distribution strips to the outer walls of multiple polymer films. Step 3: The steam evaporated from the outer wall of the membrane is pressurized and heated by a steam compressor and delivered to multiple gas equalization mechanisms. Then, the steam is evenly introduced into multiple polymer membranes through the gas equalization mechanisms. The steam inside the polymer membranes exchanges heat with the liquid on the outer wall of the polymer membranes and evaporates. Step 4: Then, the concentrate is obtained at the bottom of the tank. The concentrate at the bottom of the tank enters the distribution box again through the circulating liquid pump and circulating liquid pipeline for evaporation. The concentration of the concentrate at the bottom of the tank is detected by the concentration sensor. When the concentration value is greater than the preset value, the concentrate is pumped from the concentrate output pipe to the external concentrate buffer tank. By adding the reagent to the concentrate buffer tank and then filtering the liquid in the concentrate buffer tank, the solid and liquid are separated. The separated filter residue is collected separately and outsourced for processing, while the separated filtrate is sent to the raw liquid storage tank and heat-exchanged again before entering the tank. Step 5: The condensate inside the polymer film enters the condensation box through the condensate manifold, and the condensate exchanges heat with the raw liquid entering the inlet pipe through the second heat exchanger.

[0015] In summary, this application includes the following beneficial technical effects: The liquid feed enters the tank through the inlet pipe, then flows onto the outer wall of multiple thin-film membrane modules. Under gravity, the liquid falls naturally down the surface of the membrane modules, forming a uniform liquid film. The steam evaporating from the outer wall of the membrane modules is drawn into a steam compressor through a pipe for compression. The steam compressor pressurizes and heats the steam evaporated from the outer wall of the membrane modules and delivers it to multiple gas equalization mechanisms. These mechanisms evenly distribute the high-temperature steam to the corresponding membrane modules. At this point, the high-temperature steam inside the membrane modules exchanges heat with the liquid feed on the outer wall of the membrane modules, causing the membrane modules to expand and become gas-filled, increasing the surface area and heat exchange area. This cycle continues, resulting in a concentrated liquid at the bottom of the tank and condensate at the condensate collection mechanism. By utilizing the steam evaporated from the liquid feed, which is pressurized and heated by the steam compressor, and then used to exchange heat with the liquid feed itself, the steam is effectively utilized without the need to introduce a large amount of external high-temperature steam for heat exchange, thus saving costs to a certain extent. Attached Figure Description

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

[0017] Figure 2 This is a schematic diagram of the overall internal structure of the tank in an embodiment of this application.

[0018] Figure 3 This is an exploded view of the structure of the distribution box and the water distribution strip in the embodiments of this application.

[0019] Figure 4 This is a partial structural cross-sectional view of the polymer film in the embodiments of this application.

[0020] Figure 5 This is a cross-sectional view of the overall structure of the uniformly distributed box in the embodiments of this application.

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

[0022] Explanation of reference numerals in the attached drawings: 1. Tank body; 2. Water distribution mechanism; 201. Distribution box; 202. Water distribution strip; 3. Membrane assembly; 31. Polymer membrane; 4. Steam compressor; 5. Condensate collection mechanism; 51. Condensate manifold; 52. Condensate box; 6. Inlet pipe; 8. Concentrate outlet pipe; 9. First heat exchanger; 10. Steam delivery pipe; 11. Water inlet; 12. Water distribution hole; 13. Adjusting plate; 14. Adjusting hole; 15. Float; 16. Pull rope; 17. 18. Steam inlet; 19. Vacuum distribution hole; 20. Second heat exchanger; 21. Circulating liquid pipeline; 22. Circulating liquid pump body; 23. Water channel; 231. Dotted water channel; 232. Wavy water channel; 233. Straight water channel; 24. Water outlet; 25. Guide plate; 26. Telescopic rod; 27. Slide groove; 28. Sliding block; 29. ​​Guide pulley; 30. Spring; 32. Micropore; 33. Connecting pipe; 34. Flange; 35. Water collector; 36. Condensate branch pipe. Detailed Implementation

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

[0024] This application discloses a falling film thin-film evaporation system. (Refer to...) Figure 1 and Figure 2 The falling film thin-film evaporation system includes a tank 1, a thin film assembly 3, a steam compressor 4, a gas equalization mechanism, and a condensate collection mechanism 5. The cross-section of the tank 1 is rectangular. In other embodiments, the cross-section of the tank 1 can be circular or other shapes. During operation, the tank 1 is under negative pressure with a pressure value of -1 kPa to -95 kPa. The material of the negative pressure tank 1 is not limited to carbon steel, 304 stainless steel, 316L stainless steel, titanium, aluminum alloy, etc.

[0025] Reference Figure 1 and Figure 2 The upper end of the tank body 1 is connected to an inlet pipe 6 for feeding liquid. The membrane groups 3 are all installed inside the tank body 1. There are multiple membrane groups 3 distributed inside the tank body 1. The liquid entering through the inlet pipe 6 flows along the outer wall of the multiple membrane 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 1 through a pipe, so that the steam generated by the evaporation of the liquid can be drawn into the steam compressor 4. The gas equalization mechanism corresponds to the diaphragm group 3 one by one. The gas equalization mechanism is set in the corresponding diaphragm group 3. Each gas equalization mechanism is connected to the output end of the steam compressor 4. The gas equalization mechanism is used to uniformly introduce the high temperature steam output by the steam compressor 4 into the corresponding diaphragm group 3. The condensate collection mechanism 5 is set on the tank 1. The condensate collection mechanism 5 is used to collect the condensate in multiple diaphragm groups 3.

[0027] During operation, the liquid feed is introduced into the upper part of the tank 1 through the inlet pipe 6. The liquid then flows onto the outer walls of multiple membrane groups 3. Under gravity, the liquid flows from top to bottom along the outer walls of the membrane groups 3 to form a liquid film. Initially, external high-temperature steam is introduced into the tank 1 to heat the liquid on the outer walls of the membrane groups 3. The steam evaporating from the outer walls of the membrane groups 3 is drawn into the steam compressor 4 through pipes for compression. The steam compressor 4 pressurizes and heats the steam evaporating from the outer walls of the membrane groups 3 and delivers it to each gas equalization mechanism. The high-temperature steam is then evenly distributed to the corresponding membrane groups 3 through the gas equalization mechanism. At this point, the high-temperature steam in the membrane group 3 interacts with the membrane groups... The liquid on the outer wall undergoes heat exchange and evaporation. At this time, the input of external high-temperature steam can be reduced or stopped. The inside of the film group 3 expands and becomes air-filled, which increases the surface area and heat exchange area. Under negative pressure, the liquid will evaporate rapidly. This cycle continues, resulting in concentrated liquid at the bottom of the tank 1 and condensate at the condensate collection mechanism 5. This application utilizes the steam from the liquid evaporation to enter the steam compressor 4 for pressurization and heating, and then uses the liquid itself for heat exchange and evaporation, thereby achieving effective utilization of the evaporated steam. There is no need to introduce a large amount of external high-temperature steam to exchange heat with the liquid, which saves costs to a certain extent.

[0028] Specifically, when the liquid material initially enters the tank 1 for evaporation, external high-temperature steam can be introduced into the tank 1 to heat the liquid material on the outer wall of the membrane group 3. After the steam compressor 4 extracts the steam and pressurizes it to deliver it to each membrane 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 used can be greatly reduced, thereby achieving the effect of saving costs.

[0029] Reference Figure 2 and Figure 3 To facilitate sufficient heat exchange between the liquid and high-temperature steam, multiple film groups 3 are arranged in two rows at intervals and opposite each other to allow steam to flow upwards. Each film group 3 includes multiple polymer films 31, which are arranged horizontally in sequence inside the tank 1, with the arrangement direction of the polymer films 31 parallel to the length direction of the tank 1. Specifically, the polymer films 31 are cuboid or cubic in shape and are hung below the water equalization mechanism 2. The thickness of the polymer films 31 is 0.01mm-1mm, and the surface of the polymer films 31 is smooth and not prone to crusting. The polymer film 31 material is resistant to high temperature and corrosion, and has a high thermal conductivity. Its material is not limited to one or more of the following molecular materials: PP, PE, PTFE, FEP, PEEK, PA, PS, graphite, silicon carbide, aluminum, silver, and titanium. Among them, PP refers to polypropylene; PE refers to polyethylene; PTFE refers to polytetrafluoroethylene; FEP refers to fluorinated ethylene propylene copolymer; PEEK refers to polyether ether ketone; PA refers to polyamide; and PS refers to polystyrene.

[0030] Reference Figure 3 and Figure 4 The inner wall of the polymer film 31 is provided with water channels 23. The water channels 23 include multiple dotted water channels 231, wavy water channels 232, and straight water channels 233, which are sequentially hot-pressed from top to bottom. The dotted 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 integrally hot-pressed, which helps to ensure the formation of the dotted water channels 231, wavy water channels 232, and straight water channels 233 inside the film.

[0031] Since the high-temperature steam entering the polymer film 31 is in a gaseous state, it easily accumulates under the action of multiple wave channels 231. The accumulated high-temperature steam falls off and flows along the wave-shaped flow channel formed by multiple wave channels 232 to multiple straight channels 233. Then it enters the condensate collection mechanism 5 from the straight channels 233. This can uniformly cool and guide the high-temperature steam entering the polymer film 31, which helps to improve the evaporation effect.

[0032] Reference Figure 2 and Figure 3 To facilitate the uniform distribution of the liquid entering through the 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 equalization mechanism 2. The water equalization mechanism 2 is installed inside the tank 1 and corresponds one-to-one with the film group 3. The water equalization mechanism 2 is located above the corresponding film group 3. The installation of the water equalization mechanism 2 helps to uniformly distribute the liquid entering through the inlet pipe 6 to the outer walls of the corresponding film group 3, so that the liquid can flow from top to bottom in a film-like manner along the outer walls of the film group 3.

[0033] Reference Figure 2 and Figure 3 Specifically, the water distribution mechanism 2 includes a distribution box 201 and a water distribution strip 202. The distribution box 201 is fixedly installed at the upper end inside the tank body 1 and located above the corresponding membrane group 3. Further, the cross-section of the distribution box 201 is rectangular. The liquid inlet pipe 6 is fixedly inserted into the tank body 1 and located between two rows of membrane groups 3. Each of the multiple distribution boxes 201 has a first branch pipe (not shown in the figure) distributed above it. Each first branch pipe is connected to the liquid inlet pipe 6, thereby helping the liquid in the liquid inlet pipe 6 to flow into the multiple distribution boxes 201. The first branch pipe is located above the corresponding distribution box 201, so that the flowability of the liquid in the distribution box 201 and the vibration of the distribution box 201 do not affect the liquid inlet pipe 6. The bottom wall of the distribution box 201 has multiple water passage holes 11 (see reference). Figure 5 ).

[0034] Reference Figure 2 and Figure 3Multiple water distribution strips 202 are provided and located below the corresponding distribution box 201. The arrangement direction of the multiple water distribution 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 distribution strips 202 is perpendicular to the arrangement direction of the multiple water distribution strips 202. The multiple water distribution strips 202 are connected in series and squeezed and fixed in the tank 1 by multiple screws. A clamping space is formed between adjacent water distribution strips 202 in the water distribution mechanism 2. The clamping space corresponds one-to-one with the polymer film 31. The upper end of the polymer film 31 is located in the corresponding clamping space. The upper end of the polymer film 31 between adjacent water distribution strips 202 is clamped and fixed. The water distribution strips 202 have multiple water distribution holes 12. The arrangement direction of the multiple water distribution holes 12 is parallel to the length direction of the corresponding water distribution strip 202.

[0035] Reference Figure 2 and Figure 3 In the water distribution mechanism 2, multiple water distribution strips 202 are squeezed in sequence to form a water inlet surface. The distribution box 201 covers the water inlet surface formed by the multiple water distribution 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 distribution 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 distribution strips 202, so that the liquid will not flow to other positions in the tank 1.

[0036] When the liquid in the inlet pipe 6 enters the distribution box 201 through the first branch pipe, the liquid in the distribution box 201 flows evenly through multiple water holes 11 to the inlet level surface formed by multiple water distribution strips 202 below. Then, the liquid flows through the water distribution holes 12 on the multiple water distribution strips 202 to the corresponding polymer film 31, which helps to make the liquid flow evenly from top to bottom along the outer wall 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 4The water distribution strip 202 is made of inorganic or organic materials, and the material is not limited to PP, PE, PS, PA, PSE, PTFE, iron, stainless steel, aluminum, titanium, gold, silver, fiberglass, graphite, silicon carbide, etc.; it has the advantages of good corrosion resistance, low cost, readily available materials, and high practicality. Furthermore, the water distribution strip 202 can be composed of two water distribution half-strips spliced ​​together by male and female snap fasteners, or it can be a complete rectangular strip. In the embodiments of this application, the form of the water distribution strip 202 is not limited. When the water distribution strip 202 is composed of two water distribution half strips, multiple abutting partitions are integrally formed on the side of the two water distribution half strips that are close to each other. Multiple water distribution holes 12 are formed by the abutting of the partitions in pairs. The water distribution half strip can also be composed of multiple strips spliced ​​together. This type of water distribution strip 202 is easy to assemble and disassemble and can be spliced ​​arbitrarily as needed. When the water distribution strip 202 is in the form of a complete rectangular strip, multiple holes are opened on the rectangular strip to form multiple water distribution holes 12. This type of water distribution 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 from the steam compressor 4 into multiple polymer films 31, the gas equalization mechanism includes multiple gas equalization strips 17. Each gas equalization strip 17 corresponds one-to-one with a polymer film 31 in the corresponding film group 3. A steam inlet 18 is provided on the side wall of each polymer film 31. The gas equalization strips 17 are installed within the steam inlets 18 of the corresponding polymer film 31. The gas equalization strips 17 extend vertically, and adjacent gas equalization strips 17 abut against each other across a gap in the polymer film 31 to form an air inlet plane. A flange 34 is fixedly installed at the air inlet plane, covering the air inlet plane to form a sealed space. The output end of the steam compressor 4 is connected to a connecting pipe 33, which extends into the tank body 1 between two rows of film groups 3. The air inlet planes of the two rows of film groups 3 are located on adjacent sides, and the flange 34 of each film group 3 is connected to the connecting pipe 33. To facilitate the installation of the gas equalization strips 17, multiple gas equalization strips 17 are connected in series and pressed into the tank body 1 by multiple screws, and adjacent gas equalization strips 17 are pressed against each other; the gas equalization strips 17 have multiple gas equalization holes 19, and the arrangement direction of the multiple gas equalization holes 19 is parallel to the length direction of the gas equalization strips 17.

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

[0040] Reference Figure 3 and Figure 4The air distribution strip 17 is made of inorganic or organic materials, and the material is not limited to PP, PE, PS, PA, PSE, PTFE, iron, stainless steel, aluminum, titanium, gold, silver, fiberglass, graphite, silicon carbide, etc.; 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 air distribution half strips spliced ​​together by male and female fasteners, or it can be a complete rectangular strip. In the embodiments of this application, the form of the air distribution strip 17 is not limited. When the air equalization strip 17 is composed of two air equalization half strips, multiple abutting pieces are integrally formed on the side of the two air equalization half strips that are close to each other, and multiple air equalization holes 19 are formed by the abutting pieces abutting each other in pairs. The air equalization half strip can be spliced ​​together from multiple strips. This type of air equalization strip 17 is easy to assemble and disassemble and can be spliced ​​together as needed. When the air equalization strip 17 is in the form of a complete rectangular strip, multiple holes are opened on the rectangular strip to form multiple air equalization holes 19. This type of air equalization strip 17 does not require splicing and is easy to install.

[0041] Reference Figure 1 and Figure 2 To facilitate the collection of condensate, the condensate collection mechanism 5 includes a condensate manifold 51 and a condensate box 52. The condensate manifold 51 is fixedly installed on the tank body 1. A condensate branch pipe 36 is connected to the condensate manifold 51. There are two condensate branch pipes 36, which are located below two rows of multiple membrane groups 3. The condensate box 52 is located outside the tank body 1. The condensate manifold 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, thereby facilitating the achievement of a negative pressure state inside the tank body 1.

[0042] Reference Figure 2 and Figure 4 Each polymer film 31 has a water outlet hole 24 on its lower sidewall, and a guide plate 25 is fixedly installed on the lower inner sidewall of each polymer film 31. The guide plate 25 is aligned with and connected to the water outlet hole 24 in the corresponding polymer film 31. 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 in sequence to form an internal horizontal sealed channel to facilitate the flow of condensate. Specifically, the guide plate 25 is provided with multiple channels for discharging condensate. The end of each straight channel 233 away from the wave channel 232 is connected to the channel on the guide plate 25 so that the condensate in the polymer film 31 can enter the water outlet hole 24 through the channel on the guide plate 25.

[0043] Reference Figure 1 and Figure 4Each group of membranes 3 has a water collector 35 distributed below multiple polymer membranes 31. The water collector 35 includes an abutment ring and a connecting pipe. The abutment ring is circular, and the axis of the connecting pipe is perpendicular to the axis of the abutment ring and is connected to the inside of the abutment ring. The abutment ring is clamped between the guide plates 25 in any two adjacent polymer membranes 31 in the membrane group 3. Optimally, the abutment ring is clamped between the guide plates 25 in the two middle polymer membranes 31 in the membrane group 3 to facilitate uniform discharge of condensate. The axis of the abutment ring is parallel to the axis of the multiple guide plates 25, allowing the multiple guide plates 25 to communicate with the water collector 35. Specifically, the multiple guide plates 25 and the abutment ring can be connected and secured together by screws. The end of the connecting pipe away from the abutment ring is connected to the lower condensate branch pipe 36, thereby facilitating the transport of condensate to the condensation box 52 through the condensate branch pipe 36 and the condensate manifold 51. The flow guide plate 25 is not limited to one or more of the following materials: PP, PE, PTFE, FEP, PEEK, PA, PS, graphite, silicon carbide, aluminum, silver, and titanium. The flow guide plate 25 facilitates the flow of condensate in the polymer film 31 through the condensate manifold 51.

[0044] The high-temperature steam inside the polymer film 31 exchanges heat with the liquid material on the outer surface of the polymer film 31, causing the high-temperature steam inside the polymer film 31 to condense into condensate. Then, the condensate enters the water collector 35 from the guide plate 25 along the water channel 23, and then enters the condensate branch pipe 36 and condensate manifold 51 from the corresponding water collector 35. Finally, it enters the condensation box 52 from the condensate manifold 51.

[0045] Reference Figure 1 and Figure 2 To facilitate full utilization of the condensate temperature, the falling film thin-film evaporation system also includes a second heat exchanger 20. The condenser 52 is connected to the second heat exchanger 20 via a pipe. The input end of the second heat exchanger 20 is connected to a first raw liquid inlet pipe for connection to 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 helping to utilize the waste heat of the condensate to heat the liquid entering the liquid inlet pipe 6, which helps to save costs.

[0046] Reference Figure 1 and Figure 2To facilitate sufficient heating of the incoming liquid, the falling film evaporation system also includes a first heat exchanger 9, and a second heat exchanger 20 connected in parallel with the first heat exchanger 9. The first heat exchanger 9 is connected to a steam delivery pipe 10 for conveying external high-temperature steam. The input end of the first heat exchanger 9 is connected to a second raw liquid inlet pipe for connecting to the raw liquid storage tank, and the output end of the first heat exchanger 9 is connected to an inlet pipe 6. This allows the external high-temperature steam delivered from the steam delivery pipe 10 to exchange heat with the liquid entering the inlet pipe 6 via the first heat exchanger 9, thereby ensuring rapid evaporation of the liquid after it enters the tank 1. In use, the first heat exchanger 9 is only activated for steam heat exchange when the temperature of the raw liquid entering the tank 1 does not reach the evaporation temperature. In other embodiments, to ensure sufficient heating of the liquid on the outer wall of the polymer film 31, the steam delivery pipe 10 can also be directly connected to the interior of the tank 1.

[0047] Reference Figure 1 and Figure 2 Specifically, both the first heat exchanger 9 and the second heat exchanger 20 are plate heat exchangers. The raw liquid is stored in a raw liquid storage tank. After being filtered by a filter press, the raw liquid enters the first raw liquid inlet pipe and the second raw liquid inlet pipe respectively under the action of a water pump, so as 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 in the figure) is installed at the bottom of tank 1 to detect the concentration of the concentrate. The concentration sensor is wirelessly connected to an external control platform to transmit the concentration detection value to the external control platform. A concentrate output pipe 8 is connected to the bottom of tank 1, and a concentrate pump is installed on the concentrate output pipe 8. The concentrate output pipe 8 is used to connect to an external concentrate buffer tank. By adding reagents to the concentrate buffer tank and then filtering the liquid in the concentrate buffer tank, solid-liquid separation is achieved. The separated filter residue is collected separately and outsourced for processing, while the separated filtrate is transported to the raw liquid storage tank, where it undergoes heat exchange again before entering tank 1, thereby ensuring the evaporation effect.

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

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

[0051] Reference Figure 3 and Figure 5 An adjusting plate 13 is slidably disposed inside 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. Specifically, the sliding direction of the adjusting plate 13 is parallel to the arrangement direction of the multiple polymer films 31 in the film group 3. The adjusting plate 13 abuts against the bottom wall of the uniform distribution box 201. Multiple telescopic rods 26 are fixed between the adjusting 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 adjusting plate 13. An adjusting hole 14 is provided on the adjusting plate 13. The adjusting hole 14 corresponds one-to-one with the water passage hole 11. A sliding 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 slidably disposed 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 detach from the slide groove 27. The lower inner wall of the slide groove 27 is located above the adjustment plate 13. Specifically, the height of the lower inner wall of the slide groove 27 is set as needed.

[0053] Reference Figure 5 and Figure 6 A float plate 15 is fixed on the slider 28, so that the float plate 15 and the distribution box 201 can slide relative to each other. The sliding direction of the float plate 15 is parallel to the depth direction of the distribution box 201. The float plate 15 is located above the adjustment plate 13. A pull rope 16 is fixed between the float plate 15 and the adjustment 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 distribution box 201 near the float plate 15. The guide pulley 29 is located below the float plate 15. The pull rope 16 between the adjustment plate 13 and the float plate 15 slides and overlaps on the guide pulley 29.

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

[0055] Reference Figure 5 and Figure 6 In order to ensure that the remaining liquid in the distribution box 201 can flow out when the float 15 is at the bottom and the water passage 11 is closed by the adjusting plate 13, micro-holes 32 are provided on the bottom wall at both ends of the distribution box 201. The adjusting plate 13 is located between two micro-holes 32. The cross-section of the micro-holes 32 is much smaller than the cross-section of the water passage 11, and the adjusting plate 13 is always misaligned with the micro-holes 32 at both ends.

[0056] When the liquid initially enters the distribution box 201 from the inlet pipe 6, the spring 30 is in its natural state, and the adjusting plate 13 closes the water passage 11. Only a very small amount of the liquid can flow out through the micro-holes 32. As the amount of liquid gradually increases, the liquid level in the distribution box 201 rises. When the liquid level rises to contact the bottom wall of the float plate 15, the liquid will drive the float plate 15 to rise as the liquid level continues to rise. During the upward movement of the float plate 15, the adjusting plate 13 is pulled by the pull rope 16 to slide towards the float plate 15, compressing the spring 30. Gradually, the adjusting hole 14 is aligned with the corresponding water passage 11. At this time, the liquid in the distribution box 201 can flow quickly through multiple water passages 11 to the water distribution strip 202 below. This helps to solve the problem that when the liquid first enters the distribution box 201 or when the amount of liquid is small, the liquid only flows out quickly from some of the water passages 11 on the bottom wall of the distribution box 201, resulting in uneven evaporation.

[0057] The implementation principle of this application embodiment is as follows: During operation, the external high-temperature steam delivered by the steam conveying pipe 10 is exchanged with the liquid entering the liquid inlet pipe 6 through the first heat exchanger 9. After heat exchange, the liquid is input into the tank 1 through the liquid inlet pipe 6. Then, the liquid flows into each distribution box 201 through the first branch pipe. At this time, the spring 30 is in its natural state, and the adjusting plate 13 closes the water passage hole 11. Only a very small portion of the liquid entering the distribution box 201 can flow out through the micropore 32. As the liquid gradually increases, the liquid level in the 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. During the upward movement of the float plate 15, the adjusting plate 13 is pulled by the pull rope 16 to slide towards the float plate 15. Then, the adjusting hole 14 is gradually aligned with the corresponding water inlet 11. At this time, the liquid in the distribution box 201 can simultaneously and quickly flow through multiple water inlets 11 to the water distribution strip 202 below. Then, the liquid flows through the water distribution holes 12 on the multiple water distribution strips 202 to the outer wall of multiple polymer films 31. In the initial state, external high-temperature steam can also be directly introduced into the tank 1 to heat and evaporate the liquid. The steam compressor 4 pressurizes and heats the steam evaporated on the outer wall of the film and delivers it to multiple air inlet planes through the connecting pipe 33. Then, the high-temperature steam enters the multiple polymer films 31 evenly through the air distribution holes 19 on the multiple air distribution strips 17. The high-temperature steam in the polymer film 31 exchanges heat with the liquid on the outer wall of the polymer film 31 and evaporates. Then, the introduction of external high-temperature steam into the tank 1 can be reduced or stopped.

[0058] Then, concentrated liquid is obtained at the bottom wall of tank 1. The concentration of the concentrated liquid at the bottom of tank 1 is detected by a conductivity sensor or turbidity sensor at the bottom of tank 1. When the concentration detection value is less than the preset value, the concentrated liquid at the bottom of tank 1 re-enters the distribution box 201 through the circulating liquid pump 22 and the circulating liquid pipe 21 for evaporation. When the concentration detection value is greater than the preset value, the concentrated liquid is pumped from the concentrated liquid output pipe 8 to the external concentrated liquid buffer tank for further processing by the concentrated liquid pump. The condensate in the polymer film 31 is collected in the condensate manifold 51 through the water channel 23, the guide plate 25 and the water collector 35, and then the condensate enters the condensate condenser. The condensate in the tank 52 exchanges heat with the raw liquid entering the inlet pipe 6 through the second heat exchanger 20. This allows the steam conveying pipe 10 to only transport a small amount of external high-temperature steam to the first heat exchanger 9 to exchange heat with the raw liquid entering the inlet pipe 6, thus enabling evaporation cycle. This application utilizes the steam from the evaporation of the liquid to pressurize and heat it in the steam compressor 4, and then uses the liquid itself for heat exchange and evaporation. At the same time, it utilizes the residual heat of the condensate to exchange heat with the liquid entering the inlet pipe 6, thereby achieving effective utilization of the condensate and secondary compressed steam. This helps to reduce the amount of external high-temperature steam introduced and saves costs to a certain extent.

[0059] This application also discloses a falling film thin-film evaporation process. The falling film thin-film evaporation process, using the aforementioned falling film thin-film evaporation system, includes the following steps: Step 1: The external high-temperature steam conveyed by the steam conveying pipe 10 is exchanged with the liquid entering the liquid inlet pipe 6 through the first heat exchanger 9. The liquid after heat exchange is then fed into the tank 1 through the liquid inlet pipe 6. Step 2: Next, the liquid enters into multiple distribution boxes 201 respectively, and then flows through multiple water holes 11 on the distribution box 201 to the water distribution strip 202 below. The liquid flows evenly to the outer wall of multiple polymer films 31 through the water distribution holes 12 on the multiple water distribution strip 202. Step 3: The steam evaporated from the outer wall of the film is pressurized and heated by the steam compressor 4 and delivered to multiple gas equalization mechanisms. Then, the high-temperature steam is evenly introduced into multiple polymer films 31 through the gas equalization mechanism. The high-temperature 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, the concentrated liquid is obtained at the bottom wall of the tank 1. The concentrated liquid at the bottom of the tank 1 enters the uniform distribution box 201 again through the circulating liquid pump 22 and the circulating liquid pipe 21 for evaporation. The concentration of the concentrated liquid at the bottom of the tank 1 is detected by the concentration sensor at the bottom of the tank 1. When the concentration detection value is greater than the preset value, the concentrated liquid is pumped from the concentrated liquid output pipe 8 to the external concentrated liquid buffer tank through the concentrated liquid pump. By adding the 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 processing, while the separated filtrate is sent to the original liquid storage tank and heat-exchanged again before entering the tank 1. Step 5: The condensate in the polymer film 31 enters the condensation box 52 through the condensate manifold 51, and exchanges heat with the raw liquid entering the inlet pipe 6 through the second heat exchanger 20.

[0060] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A falling film thin film evaporation system, characterized by: The system includes a tank (1), a membrane assembly (3), a steam compressor (4), a gas equalization mechanism, and a condensate collection mechanism (5). Multiple membrane assemblies (3) are installed within the tank (1). An inlet pipe (6) for supplying liquid is connected to the tank (1). The input end of the steam compressor (4) is connected to the tank (1). Each gas equalization mechanism corresponds to one membrane assembly (3) and is installed within its respective membrane assembly (3). Each gas equalization mechanism is connected to the output end of the steam compressor (4). The gas equalization mechanism is used to evenly distribute the steam output from the steam compressor (4) into the corresponding membrane assembly (5). Within the film assembly (3), the condensate collection mechanism (5) is installed on the tank body (1). The condensate collection mechanism (5) is used to collect the condensate within multiple film assemblies (3). The evaporation system also includes a water equalization mechanism (2), which corresponds one-to-one with each film assembly (3). The water equalization mechanism (2) is located above the corresponding film assembly (3). The water equalization mechanism (2) is used to uniformly guide the liquid entering through the inlet pipe (6) to the outer wall of the corresponding film assembly (3). The water equalization mechanism (2) includes a distribution box (201) and a water equalization strip (202) installed within the tank body (1). The liquid in the inlet pipe (6) flows into multiple distribution boxes (201). The bottom wall of each distribution box (201) has multiple water holes (11). The distribution box (201) is located above a water distribution strip (202), which has multiple water distribution holes (12). An adjusting plate (13) is slidably disposed inside the distribution box (201). The sliding direction of the adjusting plate (13) is parallel to the plane of the bottom wall of the distribution box (201). The adjusting plate (13) abuts against the bottom wall of the distribution box (201). An adjusting hole (14) is provided on the adjusting plate (13). The adjustment hole (14) corresponds one-to-one with the water passage hole (11). A float plate (15) is slidably arranged inside the distribution box (201). The sliding direction of the float plate (15) is parallel to the depth direction of the distribution box (201). The float plate (15) is located above the adjustment plate (13). A pull rope (16) is arranged between the float plate (15) and the adjustment plate (13). An elastic element is arranged between the bottom wall of the distribution box (201) and the adjustment plate (13). When the elastic element is in its natural state, the adjustment hole (14) is misaligned with the corresponding water passage hole (11), and the pull rope (16) is in a slack state.

2. The falling film thin-film evaporation system according to claim 1, characterized in that: The falling film thin-film evaporation system also includes a first heat exchanger (9), which is connected to a steam conveying pipe (10) for conveying external steam. The first heat exchanger (9) is used to exchange heat between the steam conveying pipe (10) and the liquid entering the inlet pipe (6).

3. The falling film thin-film evaporation system according to claim 2, characterized in that: Multiple sets of the film groups (3) are arranged in two rows and opposite each other. Each set of the film groups (3) includes multiple polymer films (31) arranged in sequence in the tank (1) along the horizontal direction.

4. A falling film thin-film evaporation system according to claim 3, characterized in that: Multiple water leveling strips (202) are provided, and the arrangement direction of the multiple water leveling strips (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 leveling strips (202), and the clamping space corresponds one-to-one with 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.

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

6. A falling film thin-film evaporation system according to claim 3, characterized in that: The gas equalization mechanism includes multiple gas equalization strips (17), each of which corresponds to a polymer film (31) in the corresponding film group (3). The sidewall of the polymer film (31) is provided with a steam inlet (18), and the gas equalization strip (17) is located in the steam inlet (18) of the corresponding polymer film (31). Adjacent gas equalization strips (17) abut against each other across the polymer film (31) to form an air inlet plane. The gas equalization strip (17) has multiple gas equalization holes (19).

7. A falling film thin-film evaporation system according to claim 5, characterized in that: The condensate collection mechanism (5) includes a condensate manifold (51) and a condensation box (52). The condensate manifold (51) is installed on the tank body (1) and is connected to a condensate branch pipe (36). The condensate branch pipe (36) is located inside the tank body (1) and below multiple sets of film groups (3). The lower ends of multiple polymer films (31) in the film group (3) are connected to the condensate branch pipe (36). The condensation box (52) is located outside the tank body (1) and is connected to the condensation box (52).

8. A falling film thin-film evaporation system according to claim 7, characterized in that: The falling film thin-film evaporation system also includes a second heat exchanger (20), and the condenser (52) is connected to the second heat exchanger (20). The second heat exchanger (20) is used to exchange heat between the condensate in the condenser (52) and the feed liquid entering the inlet pipe (6).

9. A falling film thin-film evaporation process, using the falling film thin-film evaporation system as described in claim 8, characterized in that, Includes the following steps: Step 1: The external hot steam conveyed by the steam conveying pipe (10) is exchanged with the liquid entering the liquid inlet pipe (6) through the first heat exchanger (9). The liquid after heat exchange is then fed into the tank (1) through the liquid inlet pipe (6). Step 2: Next, the liquid enters into multiple distribution boxes (201) and flows through multiple water holes (11) on the distribution box (201) to the water distribution strip (202) below. The liquid flows evenly to the outer wall of multiple polymer films (31) through the 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 delivered to multiple gas equalization mechanisms. Then the steam enters multiple polymer films (31) evenly through the gas equalization mechanism. The steam in the polymer film (31) exchanges heat with the liquid on the outer wall of the polymer film (31) for evaporation. Step 4: Then, the concentrate is obtained at the bottom wall of the tank (1). The concentrate at the bottom of the tank (1) enters the uniform distribution box (201) again through the circulating liquid pump (22) and the circulating liquid pipe (21) for evaporation. The concentration of the concentrate at the bottom of the tank (1) is detected by the concentration sensor at the bottom of the tank (1). When the concentration detection value is greater than the preset value, the concentrate is pumped from the concentrate output pipe (8) to the external concentrate buffer tank through the concentrate pump. The agent is added to the concentrate buffer tank, and then the liquid in the concentrate buffer tank is filtered to separate the solid and liquid. The separated filter residue is collected separately for outsourced treatment, while the separated filtrate is transported to the original liquid storage tank and heat exchanged again before entering the tank (1). Step 5: The condensate in the polymer film (31) enters the condenser box (52) through the condensate manifold (51), and the condensate exchanges heat with the original liquid entering the inlet pipe (6) through the second heat exchanger (20).

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