阅读说明：本技术 竖管降膜蒸发器 (Vertical tube falling film evaporator ) 是由 赵利民 王晶晶 廖昌建 王海波 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种竖管降膜蒸发器,其包括：多个蒸发单元,其相互可拆卸地连接形成矩形阵列,蒸发单元的外壳包括筒体及其两端的上封头和下封头,筒体为长方体,蒸发单元从上至下包括布膜段、加热段和分离段；第一连接组件,其将每一行蒸发单元的加热蒸汽连通；第二连接组件,其将每一行蒸发单元的冷凝水连通；以及第三连接组件,其将每一行蒸发单元的二次蒸汽连通,第三连接组件上下交错设置在每一行蒸发单元中,使得二次蒸汽在相邻的蒸发单元中逆向流动。本发明将模块化的蒸发单元可拆卸地连接为矩形阵列,并且将矩形阵列内部的加热蒸汽、冷凝水和二次蒸汽形成特定的路径连通,实现了竖管降膜蒸发器的大型化,提高了蒸发器的处理量。(The invention discloses a vertical tube falling film evaporator, which comprises: the evaporation units are detachably connected with one another to form a rectangular array, the shell of each evaporation unit comprises a barrel body and an upper end socket and a lower end socket which are arranged at two ends of the barrel body, the barrel body is a cuboid, and each evaporation unit comprises a film distribution section, a heating section and a separation section from top to bottom; the first connecting assembly is used for communicating the heating steam of each row of evaporation units; the second connecting assembly is used for communicating the condensed water of each row of evaporation units; and the third connecting assemblies are used for communicating the secondary steam of each row of evaporation units, and the third connecting assemblies are arranged in each row of evaporation units in a vertically staggered manner, so that the secondary steam reversely flows in the adjacent evaporation units. The invention detachably connects the modularized evaporation units into the rectangular array, and the heating steam, the condensed water and the secondary steam in the rectangular array form a specific path for communication, thereby realizing the large-scale of the vertical tube falling film evaporator and improving the processing capacity of the evaporator.)

1. A standpipe falling film evaporator, comprising:

the evaporation units are detachably connected with one another to form a rectangular array, the shells of the evaporation units comprise a barrel body, and an upper end socket and a lower end socket which are arranged at two ends of the barrel body, the barrel body is a cuboid, and the evaporation units comprise a film distribution section, a heating section and a separation section from top to bottom;

the first connecting assembly is used for communicating the heating steam of each row of evaporation units;

the second connecting assembly is used for communicating the condensed water of each row of evaporation units; and

and the third connecting assemblies are used for communicating the secondary steam of each row of evaporation units and are arranged in each row of evaporation units in a vertically staggered manner, so that the secondary steam reversely flows in the adjacent evaporation units.

2. The standpipe falling film evaporator of claim 1, further comprising:

the feeding main pipe is detachably connected with the liquid inlet pipes of the plurality of evaporation units respectively;

the heating steam main pipe is detachably connected with the heating steam inlet of the evaporation unit at one end of each row;

a concentrate header pipe detachably connected to the concentrate outlets of the plurality of evaporation units, respectively;

the condensed water main pipe is respectively detachably connected with the condensed water outlet of the evaporation unit at one end of each row; and

and the two secondary steam main pipes are detachably connected with secondary steam outlets at two ends of each row of evaporation units respectively, and on-off valves are arranged on the two secondary steam main pipes.

3. The standpipe falling film evaporator of claim 2, wherein the on-off valves on the two secondary steam main are periodically switched on and off alternately.

4. The standpipe falling film evaporator of claim 3, wherein the number of evaporation units is 4-50; the number of the evaporation units in each row in the rectangular array is even.

5. The standpipe falling film evaporator of claim 1, wherein the first and second connection assemblies are male and female ring assemblies; the third connecting assembly is an annular assembly.

6. The standpipe falling film evaporator of claim 5, wherein the male and female ring assembly is sealed with packing and the ring assembly is sealed with a gasket.

7. The standpipe falling film evaporator of claim 6, wherein the male and female ring assembly is sealed with a sealing ring.

8. The standpipe falling film evaporator of claim 1, further comprising:

a plurality of reinforcing rings surrounding the outside of the rectangular array formed by the plurality of evaporation units in the horizontal direction.

9. The standpipe falling film evaporator of claim 8, further comprising:

and the pull rods penetrate between two adjacent rows and/or two adjacent columns of evaporation units, and two ends of each pull rod are detachably connected to the reinforcing rings.

10. The standpipe falling film evaporator of claim 9, wherein both ends of the tension rod are connected to the reinforcing ring by fastening nuts.

11. The standpipe falling film evaporator of claim 8, wherein the number of the reinforcing rings is three; the reinforcing ring is made of section steel.

12. The standpipe falling film evaporator of claim 8, further comprising:

and the reinforcing block is connected between the side walls of two adjacent evaporation units.

13. The standpipe falling film evaporator of claim 12, wherein the reinforcing block is a cylinder or a rectangular parallelepiped, one end of the reinforcing block being fixed to a side wall of the evaporation unit.

14. The standpipe falling film evaporator of claim 1, wherein the heating section of the evaporation unit comprises an upper tube sheet, a plurality of evaporation tubes vertically arranged in the heating section, and a lower tube sheet, the upper tube sheet and the lower tube sheet being rectangular or square; and the film distribution section of the evaporation unit is provided with a liquid distributor, and the liquid distributor is positioned above the upper tube plate.

15. The standpipe falling film evaporator of claim 14, wherein the liquid distributor comprises a liquid inlet pipe, a main tank and a plurality of sub tanks which are sequentially communicated from top to bottom, the main tank and the sub tanks are both strip-shaped, the sub tanks are vertically arranged with the main tank, a plurality of first liquid distribution holes are arranged at the bottom or two sides of the main tank, and a plurality of second liquid distribution holes and liquid baffle plates are arranged at two sides of the sub tanks in a straight line.

Technical Field

The invention relates to the field of evaporation equipment, in particular to a vertical tube falling film evaporator.

Background

The vertical tube falling film evaporator is used as an efficient evaporation device, and is gradually and widely applied to the fields of seawater desalination, sewage treatment, petrochemical industry, metallurgy, light industry, food processing, medicine and the like with the unique advantages. Under the trend of energy conservation and emission reduction, the treatment capacity of the vertical tube falling-film evaporator is more and more required along with the development of national economy in the aspects of sea water desalination, sewage treatment and the like. At present, the treatment capacity of a single evaporator can only reach 200-300 tons/hour, which brings great challenges to the design, construction and operation of the vertical tube falling film evaporator.

The prior art mainly improves the heat exchange efficiency of an evaporator and increases the treatment capacity of the evaporator through the enlargement of the evaporator. First, the large-scale evaporator has been faced with the design problem of the evaporator such as the uniformity of the distribution of the gas-liquid two-phase fluid. For example, for a conventional large standpipe falling film evaporator, the most common problem is insufficient wall area distribution points. This is because the width is not large in the range of several centimeters against the wall, but it is a considerable proportion of the cross-sectional area of the container. Therefore, a complete degree of uniformity cannot be achieved for a conventional large falling film evaporator with a circular tube sheet. In addition, because the liquid has a partial velocity from the axis to the peripheral direction after the liquid collides with the baffle from the inlet pipe at the top of the vertical pipe falling film evaporator, the liquid is gathered on the distribution plate along the radial direction to the peripheral direction, so that the liquid level on the edge of the distribution plate is higher than that on the central part, and the liquid receiving amount of the pipe on the edge of the pipe plate is larger, thereby causing uneven liquid distribution. Secondly, the large size of the evaporator faces non-standard manufacturing, transportation and detachability issues.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

It is an object of the present invention to provide a standpipe falling film evaporator which improves the throughput of prior art evaporators.

Another object of the present invention is to provide a vertical tube falling film evaporator, thereby improving the problems of the prior art, such as inconvenient manufacturing and transportation of large-sized evaporators.

To achieve the above object, the present invention provides a standpipe falling-film evaporator, which comprises: the evaporation units are detachably connected with one another to form a rectangular array, the shell of each evaporation unit comprises a barrel body and an upper end socket and a lower end socket which are arranged at two ends of the barrel body, the barrel body is a cuboid, and each evaporation unit comprises a film distribution section, a heating section and a separation section from top to bottom; the first connecting assembly is used for communicating the heating steam of each row of evaporation units; the second connecting assembly is used for communicating the condensed water of each row of evaporation units; and the third connecting assemblies are used for communicating the secondary steam of each row of evaporation units, and the third connecting assemblies are arranged in each row of evaporation units in a vertically staggered manner, so that the secondary steam reversely flows in the adjacent evaporation units.

Further, among the above-mentioned technical scheme, standpipe falling film evaporator still includes: the feeding main pipe is detachably connected with the liquid inlet pipes of the plurality of evaporation units respectively; the heating steam main pipe is detachably connected with the heating steam inlet of the evaporation unit at one end of each row; a concentrate header pipe detachably connected to the concentrate outlets of the plurality of evaporation units, respectively; the condensed water main pipe is respectively detachably connected with the condensed water outlet of the evaporation unit at one end of each row; and the two secondary steam main pipes are detachably connected with secondary steam outlets at two ends of each row of evaporation units respectively, and on-off valves are arranged on the two secondary steam main pipes.

Further, in the technical scheme, the on-off valves on the two secondary steam main pipes are periodically and alternately switched on and off.

Further, in the technical scheme, the number of the evaporation units is 4-50; the number of evaporation units in each row in the rectangular array is even.

Further, in the above technical solution, the first connecting assembly and the second connecting assembly are concave-convex ring assemblies; the third connecting component is a ring component.

Further, among the above-mentioned technical scheme, the concave-convex ring subassembly adopts the packing to seal, and cyclic annular subassembly adopts the gasket to seal.

Further, among the above-mentioned technical scheme, the unsmooth ring subassembly adopts the sealing washer sealed.

Further, among the above-mentioned technical scheme, standpipe falling film evaporator still includes: and a plurality of reinforcing rings which are arranged around the outside of the rectangular array formed by the plurality of evaporation units along the horizontal direction.

Further, among the above-mentioned technical scheme, standpipe falling film evaporator still includes: and the pull rods penetrate between two adjacent rows and/or two adjacent columns of evaporation units, and two ends of each pull rod are detachably connected to the reinforcing rings.

Furthermore, among the above-mentioned technical scheme, the both ends of pull rod are passed through fastening nut and are connected on the reinforcing ring.

Further, in the above technical solution, the number of the reinforcement rings is three; the reinforcing ring is made of section steel.

Further, among the above-mentioned technical scheme, standpipe falling film evaporator still includes: and the reinforcing block is connected between the side walls of the two adjacent evaporation units.

Further, among the above-mentioned technical scheme, the boss is cylinder or cuboid, and the one end of boss is fixed on the lateral wall of evaporation unit.

Further, in the above technical solution, the heating section of the evaporation unit includes an upper tube plate, a plurality of evaporation tubes and a lower tube plate, the plurality of evaporation tubes are vertically arranged in the heating section, and the upper tube plate and the lower tube plate are rectangular or square; the film distribution section of the evaporation unit is provided with a liquid distributor which is positioned above the upper tube plate.

Further, among the above-mentioned technical scheme, liquid distributor includes from last feed liquor pipe, main tank and a plurality of minute groove that feed through in proper order down, and the main tank is rectangular form with dividing the groove, divides the groove to set up with the main tank is perpendicular, and the bottom or both sides of main tank are equipped with a plurality of first cloth liquid holes, divide the both sides in groove to be equipped with a plurality of second cloth liquid holes and the fender liquid board that are the straight line and arrange.

Compared with the prior art, the invention has one or more of the following advantages:

1. the modularized evaporation units are detachably connected into the rectangular array, and heating steam, condensed water and secondary steam in the rectangular array form a specific path for communication, so that the large-scale standpipe falling-film evaporator is realized, and the treatment capacity of the evaporator is improved.

2. Through the up-and-down staggered arrangement of the third connecting assembly, the secondary steam of the adjacent evaporation units flows in a staggered downstream and upstream manner, namely, the secondary steam in the adjacent evaporation units flows in opposite directions, the flow of the secondary steam generated by each evaporation unit on the secondary steam flow path is superposed, and the flow rate of the secondary steam is increased to enable a liquid film in an evaporation pipe of a heating section of the evaporation unit to be turbulent, so that the purposes of heat transfer enhancement and defoaming and descaling are achieved.

3. The two ends of each line of evaporation units are provided with secondary steam outlets and are respectively connected with a secondary steam main pipe, and the secondary steam main pipes at the two ends are alternately switched on and off through on-off valve control, so that the flow path of the secondary steam in each line of evaporation units is periodically reversed, the temperature distribution of the rectangular array is more uniform, the disturbance in a secondary steam channel is strengthened, and defoaming and descaling in an evaporation pipe of a heating section are facilitated.

4. The number of each row of evaporation units is even so as to ensure that the heights of the secondary steam main pipes at two ends are the same, and other equipment is convenient to integrate and connect.

5. Adopt different coupling assembling designs, when realizing easy to assemble, manufacturing, can satisfy different pressure demands, ensure the steady operation of whole evaporimeter.

6. Through fastening connection structural design such as reinforcing ring, boss, pull rod for the rectangle array that the evaporation unit formed is more firm, durable, and the bearing capacity of evaporation unit itself is higher.

7. The modular and detachable structure enables the vertical tube falling film evaporator to be more convenient to manufacture and transport, and different numbers of evaporation units can be adopted to form a rectangular array according to actual needs, so that the problems of non-standard manufacture and the like are solved.

8. The cylinder body of the evaporation unit adopts a cuboid design, is easy to process and install, and has higher overall distribution uniformity of liquid after forming a rectangular array.

9. Each evaporation unit of the rectangular array of the modular evaporation units is fed independently by using the feeding header pipe, and the liquid distributor design of each evaporation unit greatly improves the density of liquid distribution points, the geometric uniformity of distribution and the uniformity of flow among sprinkling points.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood and to make the technical means implementable in accordance with the contents of the description, and to make the above and other objects, technical features, and advantages of the present invention more comprehensible, one or more preferred embodiments are described below in detail with reference to the accompanying drawings.

Drawings

Figure 1 is a schematic diagram of the configuration of a standpipe falling-film evaporator according to an embodiment of the present invention.

Figure 2 is a schematic diagram of a top view of a standpipe falling-film evaporator according to an embodiment of the present invention.

Figure 3 is a schematic cross-sectional view of a standpipe falling-film evaporator according to an embodiment of the present invention.

Fig. 4 is a schematic flow diagram of secondary steam in a row of evaporation units according to an embodiment of the present invention.

Fig. 5 is another schematic flow diagram of secondary steam in a row of evaporation units according to an embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view of a first connection assembly according to an embodiment of the invention.

Fig. 7 is a cross-sectional schematic view of a third connection assembly according to an embodiment of the present invention.

Fig. 8 is a schematic partial cross-sectional view of an evaporation unit according to an embodiment of the present invention.

Fig. 9 is another schematic partial cross-sectional view of an evaporation unit according to an embodiment of the invention.

Description of the main reference numerals:

10-evaporation unit, 11-shell, 12-liquid distributor, 121-liquid inlet pipe, 122-main tank, 1221-first liquid distribution hole, 1222-overflow channel, 123-sub tank, 1231-second liquid distribution hole, 124-liquid baffle, 131-upper tube plate, 132-evaporation pipe, 133-lower tube plate, 21-first connection component, 211-sealing ring, 22-second connection component, 23-third connection component, 231-bolt connection, 31-feed header pipe, 32-heating steam header pipe, 33-condensation water header pipe, 34-secondary steam header pipe, 341, 342-on-off valve, 35-concentrated solution main pipe, 41-reinforcing ring, 42-pull rod, 421-fastening nut, 43-reinforcing block and 50-bracket.

Detailed Description

The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

Spatially relative terms, such as "below," "lower," "upper," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element or feature in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the figures. For example, if the items in the figures are turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" can encompass both an orientation of below and above. The article may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein should be interpreted accordingly.

In this document, the terms "first", "second", etc. are used to distinguish two different elements or portions, and are not used to define a particular position or relative relationship. In other words, the terms "first," "second," and the like may also be interchanged with one another in some embodiments.

As shown in fig. 1 to 3, a standpipe falling-film evaporator according to an embodiment of the present invention is composed of a plurality of evaporation units 10. The shell 11 of each evaporation unit 10 comprises a barrel, an upper end enclosure and a lower end enclosure at two ends of the barrel, the barrel is a cuboid, and the evaporation units 10 comprise a film distribution section, a heating section and a separation section from top to bottom. Illustratively, the cylinder body is composed of four flat plates, and the upper end socket and the lower end socket are flat plates, cones, circular arc plates or butterfly plates, but the invention is not limited thereto. A plurality of evaporation units 10 are detachably connected to each other to form a rectangular array of n columns and m rows. The standpipe falling-film evaporators shown in fig. 1 and 2 are rectangular arrays of 3 rows and 4 columns of evaporation units, to which the invention is not limited. The number of rows and columns of the rectangular array, i.e. the number of evaporation units 10, can be selected by those skilled in the art according to the actual needs, and the rows and columns in the present invention are relative expressions and can be interchanged. Preferably, but not limitatively, the number of the evaporation units 10 is 4 to 50. In a rectangular array, the evaporation units 10 are aligned at the upper and lower ends, the side walls may abut, and communicate internally to form a specific fluid channel. Illustratively, the bottom of the rectangular array is supported by a bracket 50.

Further, in one or more exemplary embodiments of the present invention, fluid passages are formed between the evaporation units 10 by the first connection assembly 21, the second connection assembly 22, and the third connection assembly 23. The first connecting assembly 21 connects the heating steam of each row of the evaporation units 10; the second connecting assembly 22 connects the condensed water of each row of evaporation units 10; the third connecting assembly 23 communicates the secondary steam of each row of evaporation units 10. The third connecting assemblies 23 are disposed in each row of the evaporation units 10 in a staggered manner (see fig. 3), so that the secondary steam flows in opposite directions in the adjacent evaporation units 10. In each row of evaporation units 10, the secondary steam of adjacent evaporation units 10 is staggered in forward flow and reverse flow, the flow of the secondary steam generated by each row of evaporation units 10 is superposed, the flow of the secondary steam generated by each evaporation unit 10 is Q, and after the secondary steam flows through n evaporation units 10 (for example, a rectangular array has n rows, and each row has n evaporation units), the flow of the secondary steam is n × Q, so that the secondary steam in the evaporation units 10 is superposed together to increase the flow rate of the secondary steam, which causes turbulence of a liquid film in the evaporation pipe, and the heat transfer coefficient is increased along with the increase of the reynolds number of the liquid, thereby achieving the purpose of enhancing heat transfer.

Further, in one or more exemplary embodiments of the present invention, the standpipe falling-film evaporator further comprises: the feeding header pipes 31 are detachably connected with the liquid inlet pipes 121 of the plurality of evaporation units 10, respectively; the heating steam main pipe 32 is respectively detachably connected with the heating steam inlets of the evaporation units 10 at one end of each row, and heating steam is independently introduced into each row, so that the heating steam is uniformly distributed; the concentrate header pipe 35 is detachably connected to the concentrate outlets of the plurality of evaporation units 10, respectively; the condensed water header pipes 33 are respectively detachably connected with the condensed water outlets of the evaporation units 10 at one end of each row; and two secondary steam main pipes 34 detachably connected to the secondary steam outlets at both ends of each row of evaporation units 10, respectively, and on-off valves 341, 342 are provided on the two secondary steam main pipes 34.

Preferably, and without limitation, as shown in connection with fig. 4 and 5, in one or more exemplary embodiments of the invention, on-off valves 341, 342 on both secondary steam manifolds 34 are periodically and alternately on-off. The on-off valves 341 and 342 are periodically and alternately turned on and off, so that the direction of the secondary steam flow path in each row of evaporation units 10 is periodically changed, and the uniform temperature distribution of the rectangular array is more facilitated. In fig. 4, the on-off valve 341 is in a closed off state, the on-off valve 342 is in an open on state, and the secondary steam flows from the right-hand evaporation unit 10 to the left-hand evaporation unit 10, and is discharged to the secondary steam header pipe via the on-off valve 342. In fig. 5, the on-off valve 341 is in an open communication state, the on-off valve 342 is in a closed communication state, and the secondary steam flows from the evaporation unit 10 on the left end to the evaporation unit 10 on the right end, and is discharged to the secondary steam header pipe through the on-off valve 341. It should be understood that the present invention is not limited thereto, and the on-off alternation of the on-off valves 341 and 342 may be performed non-periodically according to the need. For convenience of connection, it is preferable that the number of the evaporation units 10 in each row in the rectangular array is even, and the third connection assemblies 23 at both ends of each row are located at the lower parts of the evaporation units 10 (as shown in fig. 3).

As shown in fig. 6 and 7 in combination, in one or more exemplary embodiments of the present invention, the first connection assembly 21 is a high voltage connection assembly. The first connecting assembly 21 is a male-female ring pair, so that the heating steam outlet and the heating steam inlet of the adjacent evaporation units 10 are communicated, and the male-female ring pair can be sealed by a filler, preferably by a sealing ring 211, such as an O-shaped rubber sealing ring. The first connection assembly 21 may be welded on the outer sidewall of the housing 11 of the evaporation unit 10. The structure and connection mode of the second connecting component 22 are the same as those of the first connecting component 21, and are not described in detail herein. The third connecting assembly 23 is a low-pressure connecting assembly, and the third connecting assembly 23 may be a ring-shaped assembly having a rectangular cross-section and may be connected by a connecting member, such as a bolt connection 231, using a gasket seal (not shown). The third connecting assembly 23 may be welded on the outer side wall of the housing 11 of the evaporation unit 10.

Further, in one or more exemplary embodiments of the present invention, the standpipe falling-film evaporator further includes a plurality of reinforcing rings 41 which are horizontally wound around the outside of the rectangular array formed by the plurality of evaporation units 10, and which provide a pre-tightening binding effect to the rectangular array, and also provide reinforcement to the side wall of the housing 11 of the evaporation units 10. Illustratively, the reinforcement ring 41 may be made of a steel section, such as a square steel, an angle steel, an H-shaped steel, etc., and the present invention is not limited thereto. Illustratively, the number of the reinforcing rings 41 may be three, respectively surrounding the evaporation units 10 at different heights outside the rectangular array.

Further, in one or more exemplary embodiments of the present invention, the vertical tube falling film evaporator further includes a plurality of pull rods 42 penetrating between two adjacent rows and/or two columns of the evaporation units 10, and both ends of the pull rods 42 are detachably connected to the reinforcing rings 41. For example, both ends of the pull rod 42 may be coupled to the reinforcing ring 41 by fastening nuts 421.

Further, in one or more exemplary embodiments of the present invention, the standpipe falling-film evaporator further comprises a plurality of reinforcing blocks 43 connected between the side walls of the shell 11 of two adjacent evaporation units 10, so that the side walls of two adjacent evaporation units 10 form a reinforcing structure, improving the load-bearing capacity of the evaporation units. Illustratively, the reinforcing block 43 may be a cylinder or a rectangular parallelepiped, and one end of the reinforcing block 43 may be fixed to an outer sidewall of the casing 11 of the evaporation unit 10. The reinforcing block 43 may be made of a non-metallic material such as rubber or urethane, or a metallic material such as carbon steel or cast iron.

Preferably, but not by way of limitation, as shown in connection with fig. 3, 8 and 9, in one or more exemplary embodiments of the present invention, the heating section of the evaporation unit 10 includes an upper tube plate 131, a plurality of evaporation tubes 132 and a lower tube plate 133, the plurality of evaporation tubes 132 are vertically arranged in the heating section, and the upper tube plate 131 and the lower tube plate 133 are rectangular or square in shape to match the outer shell 11 of the evaporation unit 10. Illustratively, the evaporation tube 132 is hermetically connected to the upper tube plate 131 and the lower tube plate 133 by welding or expansion. The upper end of the evaporation tube 132 is provided with a flow guide device. The membrane-laying section of the evaporation unit 10 is provided with a liquid distributor 12, and the liquid distributor 12 is located above the upper tube plate 131. Exemplarily, the liquid distributor 12 includes a liquid inlet pipe 121, a main tank 122 and a plurality of sub tanks 123 sequentially connected from top to bottom, the main tank 122 and the sub tanks 123 are both long, the sub tanks 123 are perpendicular to the main tank 122, a plurality of first liquid distribution holes 1221 are disposed at the bottom or at two sides of the main tank 122, and a plurality of second liquid distribution holes 1231 and a liquid baffle 124 linearly arranged are disposed at two sides of the sub tanks 123. After the liquid distributor 12 distributes the liquid circularly entering the film distribution section in multiple stages, the film is naturally formed by gravity, and the liquid film is required to be uniform and stable, so that the phenomenon of dry wall cannot occur in the evaporation tube 132. The liquid flowing out from the plurality of sub-tanks 123 is in a film shape, the lines are distributed on the upper tube plate 131, the liquid forms a liquid level on the upper tube plate 131, and the liquid level is in horizontal plane shape and can move and distribute uniformly, so that the density of liquid distribution points, the geometric uniformity of distribution and the uniformity of flow among the sprinkling points are greatly improved.

In one or more exemplary embodiments of the present invention, the number of the sub-grooves 123 is three, and the lengths of the three sub-grooves 123 are equal, and the three sub-grooves 123 are uniformly arranged in the length direction of the main groove 122. It should be understood that there may be a plurality of main slots 122. The liquid enters the main tank 122 (primary tank) from the liquid inlet pipe 121, and flows into the three sub-tanks 123 (secondary tank) through the first liquid distribution holes 1221 of the main tank 122, so that the liquid can form six equidistant sub-tank liquid film pipe plate distribution lines on the upper pipe plate 131. The aperture of the first liquid distribution hole 1221 is larger than 5mm, preferably 10 mm-30 mm, and the aperture of the second liquid distribution hole 1231 is larger than 10mm, preferably 12 mm-36 mm.

In one or more exemplary embodiments of the present invention, the main tank 122 adopts a bottom-hole type liquid distribution structure, and the present invention is not limited thereto. The main tank 122 may also adopt a side-hole liquid distribution structure, which is advantageous for settling and collecting the solid particles and floccules in the liquid to the bottom of the main tank 122, and thus preventing the above-mentioned dirt from entering the evaporation tubes 132 to affect the heat transfer. Exemplarily, the sub-tank 123 adopts a side-hole baffle type liquid distribution structure, two sides of the sub-tank 4 are respectively provided with a plurality of second liquid distribution holes 1231 arranged linearly, liquid in the sub-tank 123 is distributed by gravity, the liquid is sprayed out from the second liquid distribution holes 1231 and then directly impacts on the liquid baffle 124, so that distribution points are distributed in a line, the main tank 122 and the sub-tank 123 are respectively provided with an overflow channel 1222, the overflow channel 1222 is an outlet weir close to the upper edge of the tank, the outlet weir can be a rectangular weir, a V-shaped weir and a round-bottom rectangular weir, and the main tank 122 can be internally provided with an impingement baffle.

In the use process of the vertical pipe falling film evaporator, materials to be evaporated enter the liquid inlet pipe 121 of the evaporation unit 10 through the feeding main pipe 31 respectively, and liquid is input into the groove type liquid distributor 12 (i.e. the liquid distributor comprising the main groove 122 and the sub-grooves 123). Since the trough-type liquid distributor 12 is composed of two stages, the main trough 122 adopts a bottom hole type or side hole type liquid distribution structure, the branch trough 123 adopts a side hole baffle type liquid distribution structure, and the main trough 122 and the branch trough 123 are provided with overflow channels 1222. The groove type liquid distributor is suitable for occasions with large liquid amount or dirty materials, the falling distance of liquid between the sub-groove 123 and the upper tube plate 131 can be small, the liquid flows down in a film shape through the liquid baffle plate 124 and is uniformly distributed on the upper tube plate 131, the original point distribution is changed into line distribution, the liquid falling in the film shape from the liquid distributor 12 forms a plurality of liquid lines which are uniformly distributed on the upper tube plate 131, and the liquid lines flow to two sides in a square surface shape, so that the square surface liquid flow is distributed on the upper tube plate 131 without dead angles, and compared with the traditional circular tube plate, the liquid distribution is more uniform. Therefore, the groove type liquid distributor has good liquid distribution performance, and has the advantages of low height, large operation elasticity, good anti-blocking performance and the like.

After entering the evaporation tubes 132, the material to be evaporated is heated and evaporated by the heating steam, and the secondary steam is collected to the secondary steam header pipes 34 at the two ends through the third connecting assembly 23 of each evaporation unit 10 and is periodically and alternately discharged. The concentrate is collected through the bottom outlet of each evaporation unit 10 and discharged to the concentrate header 35. The heating section of each evaporation unit 10 is communicated with heating steam through the first connecting assembly 21, and the heating steam enters from the heating steam header 32 and is distributed to the evaporation units 10 in the corresponding row. The condensate is collected by the second connecting assembly 22 at the lower portion of the heating section and discharged through the condensate header 33.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. Any simple modifications, equivalent changes and modifications made to the above exemplary embodiments shall fall within the scope of the present invention.