Multi-pass falling film evaporator

Abstract

The utility model discloses a multi-pass falling film evaporator. An upper port of a barrel is hinged with an upper tube box, and the lower end of the barrel is connected with a lower tube box; a plurality of heat exchange tubes are connected between an upper tube plate and a lower tube plate of the barrel; a plurality of liquid distribution discs which are isolated from one another and integrally spliced into a circle are arranged above the upper tube plate, and liquid distribution holes of each liquid distribution disc are distributed in the periphery of a tube opening of each heat exchange tube below in a regular triangle shape; a plurality of tube pass material inlet tubes are inserted into the dome of the upper tube box, and the lower ends of the tube pass material inlet tubes point to the centers of the corresponding liquid distribution discs respectively; the bottom of the lower tube box is divided into a plurality of liquid collection spaces by partition plates, each pass liquid collection space corresponds to each pass liquid distribution disc, and the lowest part of each pass liquid collection space is connected with a tube pass material outlet tube; an expanding section is arranged on the upper portion of the barrel, a shell pass steam inlet is formed in the circumference of the expanding section, a condensate water outlet is formed in the side wall of the lower portion of the barrel, and a secondary steam outlet is formed in the side wall of the middle section of the lower tube box. The evaporator is small in occupied area, convenient to overhaul, convenient to adjust and good in evaporation quality of thermosensitive media.

Description

Technical Field

[0001] The utility model relates to a falling film evaporator, in particular to a multi-pass falling film evaporator, and belongs to the technical field of evaporation equipment. Background Art

[0002] The falling film evaporator is a common device in the evaporation system. Taking the Chinese invention patent with publication number CN109589626B as an example, the falling film evaporator usually includes an upper shell, an intermediate shell, and a lower shell that are sealed and connected in sequence; an upper tube sheet is arranged at the upper end of the intermediate shell, and a lower tube sheet is arranged at the lower end. A number of evaporation tubes are evenly arranged in the intermediate shell, and the lower end of the evaporation tube is fixed in the installation opening on the lower shell. The upper part of the evaporation tube passes through the upper tube sheet and extends into the upper shell. The upper end of each evaporation tube is sealed and connected to an evaporation tube feed distributor. The feed liquid enters from the upper shell of the falling film evaporator, and is evenly distributed to each heat exchange tube through the liquid distributor. Under the action of gravity, vacuum induction and airflow, it forms a falling film along the inner wall of the tube and flows from top to bottom. During the flow process, it is heated and vaporized by the shell heating medium.

[0003] Tobacco extract is a heat-sensitive substance. The two most critical factors affecting the quality of the concentrate are evaporation temperature and material residence time. In existing engineering projects, multi-effect evaporation is mainly used, that is, multiple devices with different heat exchange areas are used to purify and concentrate the tobacco extract in sequence. There are the following problems:

[0004] 1. When multiple falling film evaporators are used, the equipment occupies a large area, which wastes space and civil engineering costs;

[0005] 2. The sealing method between the tube box and the heat exchange tube of the existing multi-effect falling film evaporator mostly adopts the traditional bolt, nut and gasket form, which is inconvenient to repair and the gasket is easily damaged;

[0006] 3. The small hole structure of the liquid separation plate adopts the form of through holes with equal diameters at the top and bottom. The small hole flow length is long, and the liquid separation plate needs to be cleaned frequently, otherwise it will easily form hardening or even blockage;

[0007] 4. The feed inlet adopts a single-stage distribution plate, which easily causes uneven liquid distribution, eventually leading to excessive liquid in some heat exchange tubes and no liquid in other heat exchange tubes, unable to form a liquid film;

[0008] 5. The liquid distributor and the upper tube box are welded, which is not easy to replace and clean. When the evaporation volume of the system changes, the evaporation volume cannot be adjusted by replacing the liquid distributor alone. Utility Model Content

[0009] The purpose of this section is to summarize some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and utility model name of this application to avoid blurring the purpose of this section, specification abstract and utility model name, and such simplifications or omissions cannot be used to limit the scope of the utility model.

[0010] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0011] The utility model aims to overcome the problems existing in the prior art and provide a multi-pass falling film evaporator with compact structure, small footprint, convenient maintenance, convenient adjustment of evaporation amount and good evaporation quality for heat-sensitive media.

[0012] In order to solve the above technical problems, the utility model provides a multi-pass falling film evaporator, comprising a cylinder, the upper end of the cylinder is hinged with an upper tube box, and the lower end of the cylinder is connected to the lower tube box; the upper cross section of the inner cavity of the cylinder is provided with an upper tube plate, and the lower cross section of the inner cavity of the cylinder is provided with a lower tube plate, and the upper tube plate and the lower tube plate are connected through a plurality of evenly distributed heat exchange tubes;

[0013] A plurality of liquid distribution plates isolated from each other and integrally spliced ​​into a circle are arranged above the upper tube plate, and a plurality of liquid distribution holes are evenly distributed on the bottom wall of each liquid distribution plate, and the liquid distribution holes are distributed in the shape of regular triangles on the outer periphery of the tube openings of each heat exchange tube below;

[0014] The dome of the upper tube box is plugged with a plurality of vertically extending tube-side material inlet pipes, and the lower end of each tube-side material inlet pipe points to the center of the corresponding liquid separation plate;

[0015] The bottom of the lower tube box is divided into a plurality of liquid collecting spaces by a partition, each liquid collecting space corresponds to each liquid separation plate and the lowest point is connected to a tube material outlet pipe;

[0016] An expanded diameter section is provided at the upper part of the cylinder, a shell-side steam inlet is provided on the circumference of the expanded diameter section, a condensate outlet is provided on the lower side wall of the cylinder, and a secondary steam outlet is provided on the middle side wall of the lower tube box.

[0017] Furthermore, a first-level material distribution cone is provided at the lower end of each of the pipe-side material inlet pipes, and each first-level material cone is a right circular cone and is coaxial with the corresponding pipe-side material inlet pipe.

[0018] Furthermore, among the liquid separation plates, the area of ​​the first liquid separation plate is the largest, and the areas of the following liquid separation plates decrease in sequence. The edges of the liquid separation plates of each stage stand upright and the edges of adjacent liquid separation plates are close to each other.

[0019] Furthermore, a pair of handles are welded to the inner wall of the edge of each liquid separation plate.

[0020] Furthermore, the shell side of the cylinder is provided with a plurality of baffles.

[0021] Furthermore, the upper and lower parts of the side walls of the cylinder are respectively provided with non-condensable gas suction ports.

[0022] Furthermore, a rotatable tower top suspension column is installed on the outer side of the upper part of the cylinder, and the lower end of the tower top suspension column is supported on the bottom support. The middle section of the tower top suspension column passes through the intermediate bracket, and the intermediate bracket is provided with a plurality of bracket sockets. A suspension column ear is welded to the outer wall of the tower top suspension column, and a positioning locking pin is inserted into the through hole of the suspension column ear, and the lower end of the positioning locking pin is inserted into a bracket socket; the upper end of the tower top suspension column extends above the upper pipe box and a lifting ear is provided at the free end.

[0023] Furthermore, the flange of the upper tube box is connected to the upper flange of the cylinder through a plurality of quick-open bolts, and an O-ring is embedded in the circumference of the upper end surface of the upper flange of the cylinder to achieve sealing with the flange of the upper tube box.

[0024] Furthermore, the liquid distribution holes of each liquid separation plate are all tapered, being wider at the top and narrower at the bottom.

[0025] Furthermore, the bottom wall of each liquid separation plate is connected to the upper tube plate via bolts.

[0026] Compared with the prior art, the utility model has achieved the following beneficial effects: 1. It adopts a compact combined structure to achieve multi-pass continuous evaporation in one device, reducing the occupied site area by more than 50%;

[0027] 2. The structure seal of quick-open bolts and O-rings is adopted, which is convenient for inspection and maintenance and saves manpower and material resources;

[0028] 3. The liquid distribution method of a primary distributor plus a secondary liquid distribution plate is adopted to ensure that a uniform liquid film can be formed on the inner wall of each heat exchange tube, which greatly improves the heat exchange efficiency and saves steam consumption compared with the traditional method;

[0029] 4. The bottom partition prevents the materials from mixing with each other, ensuring the aroma of the tobacco extract. At the same time, the position of the air outlet is controlled to prevent the material from being caught in the liquid.

[0030] 5. The small hole structure of the liquid separation plate is optimized to a cone shape and the process length is shortened by reducing the thickness, which increases the cleaning frequency of the entire system from about once every 3 days to once every 10 days;

[0031] 6. The residence time of tobacco extract in each process is shortened, the heat exchange intensity is reduced, and the concentration effect is ensured by multi-pass evaporation, which is more conducive to controlling the concentration of the concentrated liquid; the loss of heat-sensitive substances in the tobacco extract is reduced, which is conducive to maintaining the tobacco flavor. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. The drawings are only provided for reference and explanation, not for limiting the present utility model. Among them:

[0033] Figure 1 This is a front view of the multi-pass falling film evaporator of the utility model;

[0034] Figure 2 It is a cross-sectional view of the multi-pass falling film evaporator of the utility model;

[0035] Figure 3 It is a top view of the multi-pass falling film evaporator of the utility model;

[0036] Figure 4 It is a three-dimensional diagram of the upper tube box in the utility model;

[0037] Figure 5 It is a three-dimensional diagram of the secondary liquid separation plate in the utility model;

[0038] Figure 6 This is a position comparison diagram of the secondary liquid separation plate and the lower heat exchange tube in the utility model;

[0039] Figure 7 It is a three-dimensional diagram of the suspension column bracket in the utility model;

[0040] In the figure: 1. tube side material inlet pipe; 2. upper tube box; 3. primary distribution cone; 4. first pass liquid separator; 5. upper tube sheet; 6. heat exchange tube; 7. shell side steam inlet; 8. secondary steam outlet; 9. lower tube box; 9a. liquid level gauge interface; 10. tube side material outlet pipe; 11. second pass liquid separator; 12. third pass liquid separator; 13. fourth pass liquid separator; 14. fifth pass liquid separator; 15. sixth pass liquid separator; 16. baffle; 17. condensate outlet; 18. non-condensable gas suction port; 19. quick-opening bolt; 20. tower top sling; 20a. intermediate bracket; 20b. sling support ear; 20c. positioning lock pin; 21. O-ring; 22. base. DETAILED DESCRIPTION

[0041] In the following description of the utility model, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the utility model and simplifying the description, and do not mean that the device must have a specific direction.

[0042] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0044] like Figures 1 to 7 As shown, the multi-pass falling film evaporator of the utility model comprises a cylinder, the upper end of which is hingedly connected with an upper tube box 2, the lower end of which is connected with a lower tube box 9, and the lower end of which is supported on a base 22. An upper tube sheet 5 is provided in the upper cross section of the inner cavity of the cylinder, and a lower tube sheet is provided in the lower cross section of the inner cavity of the cylinder. The upper tube sheet 5 and the lower tube sheet are connected through a plurality of evenly distributed heat exchange tubes 6. An expanded diameter section is provided at the upper part of the cylinder to facilitate the entry of steam into the shell space; a shell steam inlet 7 is provided on the circumference of the expanded diameter section, and a condensate outlet 17 is provided on the lower side wall of the cylinder. The shell side of the cylinder is provided with multiple baffles 16 to extend the residence time of steam and extend the steam stroke; the steam in the shell side of the cylinder releases the latent heat of vaporization through heat exchange with the medium in the heat exchange tube 6 to become condensate, which is discharged from the condensate outlet 17 at the lower part.

[0045] The upper and lower parts of the side wall of the cylinder are respectively provided with non-condensable gas suction ports 18 for discharging the non-condensable gas in the cylinder before or during production.

[0046] A plurality of liquid separation plates which are isolated from each other and integrally spliced ​​into a circle are arranged above the upper tube plate 5. A plurality of vertically extending tube-side material inlet pipes 1 are plugged into the dome of the upper tube box 2. The lower end of each tube-side material inlet pipe 1 points to the center of the corresponding liquid separation plate, and a primary material distribution cone 3 is arranged at the lower end of each tube-side material inlet pipe 1. Each primary material cone is a right circular cone and is coaxial with the corresponding tube-side material inlet pipe 1.

[0047] The tobacco extract enters from the material inlet pipe 1 of the tube side, and then passes through the corresponding first-level distribution cone 3 for primary distribution, and then passes through the precision-machined liquid separation plate for secondary distribution. By controlling the feed amount to ensure that there is sufficient liquid height in the liquid separation plate, a falling film can be evenly formed in each heat exchange tube 6.

[0048] The bottom wall of each liquid distribution plate is evenly distributed with multiple liquid distribution holes, which are distributed in the shape of regular triangles on the outer periphery of the tube openings of each heat exchange tube 6 below. The top of the liquid distribution hole of the liquid distribution plate adopts a large chamfered form that is wide at the top and narrow at the bottom, and the chamfer angle is set to 45°. When the liquid flows through the liquid distribution hole of the liquid distribution plate, the conical structure makes the liquid flow more smoothly, and it is less likely to form eddy currents when entering the internal space of the liquid distribution hole. Due to the chamfer, the length of the process of the liquid flowing through the minimum diameter after entering the small hole is much shorter than that of the traditional structure, so it is less likely to form blockage at the small hole of the liquid distribution plate. The bottom of the small hole is chamfered to avoid the situation where burrs may be generated in the liquid distribution plate during processing, and also make the liquid discharge smoother after flowing through the small hole.

[0049] Under the premise of ensuring the overall strength of the separatory plate, the bottom plate of the separatory plate is made as thin as possible to shorten the flow length of the liquid through the separatory plate. At the same time, in order to ensure the flatness of the separatory plate after welding, the height of the weld foot of ordinary welding is reduced to about 1mm. After chamfering the surrounding area of ​​the separatory plate, argon arc welding is used to ensure the flatness after sealing and welding, and minimize the influence of welding thermal deformation on the flatness of the bottom plate of the separatory plate.

[0050] Among the liquid separation plates, the area of ​​the first-stage liquid separation plate 4 is the largest, and the areas of the following liquid separation plates decrease in sequence. The edges of the liquid separation plates of each stage stand upright and the edges of adjacent liquid separation plates are close to each other.

[0051] When the liquid separation plate is blocked, it needs to be cleaned. To facilitate disassembly and reinstallation, the bottom wall of each liquid separation plate is connected to the upper tube plate 5 by bolts, and a pair of handles are welded on the inner wall of the edge of each liquid separation plate. If the subsequent system needs to adjust the evaporation amount or replace the liquid separation plate, it is convenient to operate and reduce the replacement cost.

[0052] The small holes of the liquid separator plate are arranged in a regular triangle with the holes of the heat exchange tubes in the tube bundle assembly. The small holes of the liquid separator plate are located at the center of the hole bridge of the heat exchange tube holes of the tube sheet from a top view, thereby achieving uniform liquid distribution.

[0053] Since the upper tube box 2 is frequently disassembled, the flange of the upper tube box 2 is connected to the upper flange of the cylinder through multiple quick-open bolts 19, and an O-ring 21 is embedded in the circumference of the upper end surface of the upper flange of the cylinder to achieve sealing with the flange of the upper tube box. A separate tower top hanging column 20 is designed, which is not only convenient for disassembly and maintenance, but also avoids the problem of the flat sealing gasket losing its resilience due to excessive compression of the bolts due to repeated replacement, resulting in sealing failure.

[0054] In order to facilitate the lifting of the upper pipe box 2, a rotatable tower top hanging column 20 is installed on the outer side of the upper part of the cylinder. The lower end of the tower top hanging column 20 is supported on the bottom support, and the middle section of the tower top hanging column 20 passes through the intermediate bracket 20a. The intermediate bracket 20a is provided with a plurality of bracket insertion holes. The outer wall of the tower top hanging column 20 is welded with a hanging column support ear 20b. The through hole of the hanging column support ear 20b is plugged with a positioning lock pin 20c, and the lower end of the positioning lock pin 20c is inserted into a bracket insertion hole; the upper end of the tower top hanging column 20 extends above the upper pipe box 2 and a hanging ear is provided at the free end, and the hanging ear is located above the top center of the upper pipe box 2. When the upper pipe box 2 needs to be disassembled, the upper pipe box 2 is operated through the tower top hanging column 20. After the quick-opening bolts 19 are opened to lift the upper pipe box 2, the tower top hanging column 20 is rotated to move it away from the upper end of the cylinder body, and the positioning lock pin 20c is inserted into a bracket plug hole through the through hole of the hanging column ear 20b to lock the tower top hanging column 20. After the liquid separation plate is cleaned, it is restored. The whole process is quick and convenient, the operation difficulty is low, and the labor intensity and labor consumption are reduced.

[0055] The liquid phase space and gas phase space of the lower tube box 9 are respectively provided with a liquid level meter interface 9a for installing the liquid level meter. The bottom of the lower tube box 9 is divided into multiple liquid collection spaces by a partition. Each liquid collection space corresponds to each liquid separation plate, which is independent of each other and ensures that the liquid in each process will not mix with each other. The lowest point of each liquid collection space is respectively provided with a bottom liquid outlet and connected to a tube material outlet pipe 10 to prevent the liquid from being deposited in the equipment and affecting the fragrance of the liquid.

[0056] When the equipment is running in the evaporation concentration system, the liquid to be concentrated enters the inner cavity of the upper tube box 2 from the first-pass tube material inlet pipe 1, flows through the first-stage distribution cone 3 for primary distribution, and then falls into the first-pass liquid separation plate 4. After a certain liquid level is formed in the first-pass liquid separation plate 4, it flows out from the liquid distribution holes of the first-pass liquid separation plate 4 by relying on the liquid's own gravitational potential energy and drips onto the tube bridge of the upper tube plate 5; under the action of the liquid surface tension, the liquid diffuses from the tube bridge into the heat exchange tube 6 directly below the first-pass liquid separation plate 4, flows downward along the inner wall circumference of the heat exchange tube 6, and forms a uniform liquid film.

[0057] At this time, the shell side space of the multi-pass falling film evaporator is already filled with high-temperature steam entering from the shell side steam inlet 7. The uniform liquid film formed by the feed liquid on the inner wall of the heat exchange tube exchanges heat with the high-temperature steam in the shell side through the tube wall of the heat exchange tube 6. Part of the liquid in the liquid film vaporizes to form secondary steam after reaching the boiling point. The middle section side wall of the lower tube box 9 is provided with a secondary steam outlet 8. In order to increase the total cross-sectional area of ​​the secondary steam outlet 8, Figure 2Two secondary steam outlets 8 are provided in the heat exchange tube 6. The secondary steam formed in the heat exchange tube 6 is extracted from the secondary steam outlet 8 at the bottom under the action of the compressor in the concentration system. At this time, the liquid film in the heat exchange tube 6 continues to flow downward along the inner wall of the heat exchange tube under the dual traction of gravity and the secondary steam airflow, forming a uniform liquid film on the inner wall of the entire heat exchange tube. The concentrated liquid after the first pass enters the first pass liquid collection space corresponding to the lower tube box 9, and then is discharged from the tube material outlet pipe 10 of the first pass at the bottom, and is pumped to the top of the falling film evaporator by the fluid, enters the inner cavity of the upper tube box 2 from the tube material inlet pipe 1 of the second pass, and falls into the second pass liquid separation plate 11, and flows out from the liquid distribution holes of the second pass liquid separation plate 11, and forms a falling film in the heat exchange tube directly below the second pass liquid separation plate 11. The concentrated liquid after the second pass enters the second pass liquid collection space corresponding to the lower tube box 9, and then is discharged from the tube material outlet pipe 10 of the second pass at the bottom, and is pumped to the top of the falling film evaporator by the fluid.

[0058] By analogy, the material subsequently passes through the third-pass liquid separation plate 12, the fourth-pass liquid separation plate 13, the fifth-pass liquid separation plate 14, and the sixth-pass liquid separation plate 15 in sequence, and finally reaches the ideal concentration and is discharged from the sixth-pass pipe material outlet pipe 10 at the bottom into the system for the next step of processing.

[0059] The shell-side steam enters the shell-side space from the shell-side steam inlet 7, passes through the deflection of the baffle 16, exchanges heat with the liquid in the heat exchange tubes arranged in an equilateral triangle, releases the latent heat of vaporization, and is discharged from the condensate outlet 17 after being converted into condensed water. The gas that cannot be condensed is discharged outside the equipment from the non-condensable gas suction port 18.

[0060] When the evaporation volume of the equipment begins to decrease and the liquid separation plate needs to be cleaned, the quick-opening bolt 19 can be easily opened, the upper pipe box 2 can be lifted up through the tower top hanging column 20, and then the liquid separation plate can be taken out for cleaning; during the entire life cycle of the evaporator, the upper pipe box may need to be disassembled frequently, so a sealing form of quick-opening bolts 19 plus O-rings 21 is adopted, and the non-metallic seal will not lose its resilience due to frequent squeezing, resulting in sealing failure.

[0061] The above description is only the preferred feasible embodiment of the utility model, which shows and describes the basic principle, main features and advantages of the utility model, but does not limit the scope of patent protection of the utility model. The technicians in this industry should understand that the utility model is not limited by the above embodiments. In addition to the above embodiments, the utility model can also have other implementation modes without departing from the spirit and scope of the utility model. The utility model will also have various changes and improvements. All technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the utility model. The scope of protection required by the utility model is defined by the attached claims and their equivalents. The technical features not described in the utility model can be achieved by or using existing technologies, which will not be repeated here.

Claims

1. A multi-pass falling film evaporator, comprising a cylinder, characterized in that: The upper port of the cylinder is hinged with an upper tube box, and the lower port of the cylinder is connected to the lower tube box; the upper cross section of the inner cavity of the cylinder is provided with an upper tube sheet, and the lower cross section of the inner cavity of the cylinder is provided with a lower tube sheet, and the upper tube sheet and the lower tube sheet are connected through a plurality of evenly distributed heat exchange tubes; A plurality of liquid distribution plates isolated from each other and integrally spliced ​​into a circle are arranged above the upper tube plate, and a plurality of liquid distribution holes are evenly distributed on the bottom wall of each liquid distribution plate, and the liquid distribution holes are distributed in the shape of regular triangles on the outer periphery of the tube openings of each heat exchange tube below; The dome of the upper tube box is plugged with a plurality of vertically extending tube-side material inlet pipes, and the lower end of each tube-side material inlet pipe points to the center of the corresponding liquid separation plate; The bottom of the lower tube box is divided into a plurality of liquid collecting spaces by a partition, each liquid collecting space corresponds to each liquid separation plate and the lowest point is connected to a tube material outlet pipe; An expanded diameter section is provided at the upper part of the cylinder, a shell-side steam inlet is provided on the circumference of the expanded diameter section, a condensate outlet is provided on the lower side wall of the cylinder, and a secondary steam outlet is provided on the middle side wall of the lower tube box.

2. The multi-pass falling film evaporator according to claim 1, characterized in that: A first-level material distribution cone is respectively arranged at the lower end of each of the pipe-side material inlet pipes, and each first-level material cone is a right circular cone and is coaxial with the corresponding pipe-side material inlet pipe.

3. The multi-pass falling film evaporator according to claim 1, characterized in that: Among the liquid separation plates, the area of ​​the first liquid separation plate is the largest, and the areas of the following liquid separation plates decrease in sequence. The edges of the liquid separation plates of each stage stand upright and the edges of adjacent liquid separation plates are close to each other.

4. The multi-pass falling film evaporator according to claim 3, characterized in that: A pair of handles are respectively welded on the inner wall of the edge of each liquid separation plate.

5. The multi-pass falling film evaporator according to claim 1, characterized in that: The shell side of the cylinder is provided with a plurality of baffles.

6. The multi-pass falling film evaporator according to claim 1, characterized in that: The upper part and the lower part of the side wall of the cylinder are respectively provided with non-condensable gas suction ports.

7. The multi-pass falling film evaporator according to claim 1, characterized in that: A rotatable tower top suspension column is installed on the outer side of the upper part of the cylinder, and the lower end of the tower top suspension column is supported on the bottom support. The middle section of the tower top suspension column passes through the intermediate bracket, and the intermediate bracket is provided with a plurality of bracket insertion holes. A suspension column ear is welded to the outer wall of the tower top suspension column, and a positioning locking pin is inserted into the through hole of the suspension column ear, and the lower end of the positioning locking pin is inserted into a bracket insertion hole; the upper end of the tower top suspension column extends above the upper pipe box and a lifting ear is provided at the free end.

8. The multi-pass falling film evaporator according to claim 1, characterized in that: The flange of the upper pipe box is connected to the upper flange of the cylinder through a plurality of quick-open bolts, and an O-ring is embedded in the circumference of the upper end surface of the upper flange of the cylinder to achieve sealing with the flange of the upper pipe box.

9. The multi-pass falling film evaporator according to claim 1, characterized in that: The liquid distribution holes of each liquid separation plate are all conical in shape, being wider at the top and narrower at the bottom.

10. The multi-pass falling film evaporator according to claim 1, characterized in that: The bottom wall of each liquid separation plate is connected to the upper tube plate through bolts.

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