Multi-effect horizontal tube falling film evaporator

Abstract

The utility model relates to the technical field of hydrometallurgy water treatment, and discloses a multi-effect horizontal tube falling film evaporator which comprises a front sealing head, a rear sealing head and at least two evaporation devices, the front sealing head, the at least two evaporation devices and the rear sealing head are sequentially connected from front to back, the front sealing head is provided with a steam inlet, and the rear sealing head is provided with a steam outlet; the front tube plate and the rear tube plate are arranged in a front-back spaced mode so as to divide the interior of the evaporation device into a steam inlet chamber, an evaporation chamber and a steam exhaust chamber from front to back, and the steam exhaust chamber of the previous evaporation device is communicated with the steam inlet chamber of the next evaporation device. A steam inlet hole and a front steam outlet hole are formed in the front pipe plate, the rear pipe seal is communicated with the steam exhaust chamber through a rear liquid discharge pipe, a rear steam outlet hole is formed in the rear pipe wall, and the evaporation chamber is communicated with the steam exhaust chamber through the rear steam outlet hole; the heat exchange pipe is arranged in the evaporation chamber in a front-back extending mode and comprises an upper pipe body and a lower pipe body. The evaporator disclosed by the utility model is more uniform in liquid distribution, higher in steam utilization rate, higher in heat transfer efficiency, better in system performance and higher in water yield.

Description

Technical Field

[0001] The utility model relates to the technical field of hydrometallurgical water treatment, in particular to a multi-effect horizontal tube falling film evaporator. Background Art

[0002] Hydrometallurgical wastewater treatment is a key process for treating wastewater during metal smelting and extraction. Hydrometallurgical wastewater usually contains a variety of metal ions, mainly sodium sulfate solution. The development of hydrometallurgical wastewater treatment technology is crucial. Currently, there are mainly thermal and membrane methods. Compared with the membrane method, the multi-effect horizontal tube falling film evaporation technology in the thermal method has the advantages of good heat transfer performance, good product water quality, low scaling and low treatment cost. It is widely used in wastewater treatment, air conditioning and refrigeration and other fields.

[0003] Horizontal tube falling film evaporation is to spray the raw material liquid through the spray pipe to the horizontal tube wall at the top of the evaporator. The raw material liquid forms a falling film flow under the action of gravity. Low-pressure steam enters the horizontal tube of the evaporator to make the liquid film on the outer wall of the tube absorb heat and evaporate to produce steam. The steam in the tube is condensed into liquid through convection heat exchange. The secondary steam generated by evaporation enters the next-effect evaporator, and the unevaporated raw material liquid falls to the bottom of the evaporator and is then pumped out by the water pump, thereby realizing the process of raw material liquid concentration.

[0004] The structure of the evaporator device has a crucial impact on the performance of the falling film evaporation system. The commonly used horizontal tube evaporator device has a single liquid distribution method and tube path, which may cause problems such as uneven liquid distribution and insufficient steam utilization, resulting in poor structural heat transfer characteristics of the evaporator device, thereby affecting system performance. Vertical tube falling film evaporation has low heat transfer efficiency and is prone to scaling. At the same time, in actual engineering applications, the liquid distribution structure size and tube path are different, so it is impossible to form a modular equipment structure. Utility Model Content

[0005] The purpose of the utility model is to design a multi-effect horizontal tube falling film evaporator which can solve the above problems.

[0006] In order to achieve the above-mentioned object, the utility model provides a multi-effect horizontal tube falling film evaporator, comprising a front head, a rear head and at least two evaporation devices; the front head, the at least two evaporation devices and the rear head are connected in sequence from front to back, the front head is provided with a steam inlet, and the rear head is provided with a steam outlet;

[0007] The evaporator comprises a front tube plate, a rear tube plate, a front tube seal, a rear tube seal, a front drain pipe, a rear drain pipe and a heat exchange pipe. The front tube plate and the rear tube plate are arranged at intervals in front and back to divide the interior of the evaporator into a steam inlet chamber, an evaporation chamber and a steam exhaust chamber from front to back. In two evaporators adjacent to each other, the steam exhaust chamber of the first evaporator is connected to the steam inlet chamber of the second evaporator.

[0008] The front tube plate is provided with a steam inlet hole and a front steam exhaust hole, the front tube seal is installed on the side of the front tube plate facing the steam inlet chamber, and the front tube seal is connected with the evaporation chamber through the front steam exhaust hole and connected with the steam inlet chamber through the front liquid discharge pipe, the rear tube seal is installed on the side of the rear tube plate facing the steam exhaust chamber, the rear tube seal is connected with the steam exhaust chamber through the rear liquid discharge pipe, the rear tube plate is provided with a rear steam exhaust hole, and the evaporation chamber is connected with the steam exhaust chamber through the rear steam exhaust hole;

[0009] The heat exchange tube is arranged in the evaporation chamber along the front-to-back direction, and includes an upper tube and a lower tube. The front end of the lower tube is connected to the front tube plate and communicates with the steam inlet chamber through the steam inlet hole. The front end of the upper tube is connected to the front tube plate and communicates with the front tube seal. The rear ends of the lower tube and the upper tube are both connected to the rear tube plate and communicate with the rear tube seal.

[0010] A condensed water outlet is provided at the bottom of the steam inlet chamber, a spray device for spraying liquid is provided at the top of the evaporation chamber, and a liquid outlet is provided at the bottom of the evaporation chamber.

[0011] Furthermore, there is a spray pipe hole on the top of the evaporation chamber, and the spray device includes a spray main pipe and a plurality of spray sub-pipes extending in the front-to-back direction. The plurality of spray sub-pipes are arranged at intervals in the left-to-right direction in the same plane and are arranged above the heat exchange tube. The spray main pipe is passed through the spray pipe hole and is connected to each of the spray sub-pipes respectively.

[0012] Furthermore, a plurality of spray holes are provided at intervals along the front-to-back direction at the bottom of the spray sub-tube, and the interval size between two adjacent spray holes is 15 mm to 25 mm.

[0013] Furthermore, a spray gap is formed between the spray sub-tube and the heat exchange tube, and the front exhaust hole is arranged toward the spray gap.

[0014] Furthermore, the heat exchange tubes include multiple rows of upper tubes and multiple rows of lower tubes, and adjacent upper tubes in the same row are spaced apart in the left-right direction, and adjacent lower tubes in the same row are spaced apart in the left-right direction.

[0015] Furthermore, the upper tubes in each row adjacent to each other are arranged in a staggered manner, and the lower tubes in each row adjacent to each other are arranged in a staggered manner.

[0016] Furthermore, a first pressure detection device is provided in the front head and / or the rear head.

[0017] Furthermore, a second pressure detection device and / or a temperature detection device is also provided in the evaporation device.

[0018] Furthermore, the evaporation device also includes a wire mesh demister for intercepting salt water mist, and the wire mesh demister is arranged on the rear exhaust hole.

[0019] Furthermore, the outer bottom of the evaporation device is also provided with a bracket for lifting it in suspension.

[0020] Compared with the prior art, the multi-effect horizontal tube falling film evaporator of the utility model has the following beneficial effects:

[0021] The multi-effect horizontal tube falling film evaporator of the embodiment of the utility model is that the wastewater raw liquid of the evaporator of the utility model can enter each evaporation device at the same time for evaporation and concentration; and through the front tube plate, front tube seal, rear tube plate and rear tube seal, the steam generated by the evaporation of the liquid in the front evaporation device and the steam that is not completely condensed after passing through the front evaporation device can be effectively mixed and then passed into the next evaporation device, which can reduce the amount of steam used and reduce the amount of condensation during the steam movement, which not only reduces the risk of scaling and improves the steam utilization rate, but also improves the evaporation efficiency and system performance. This evaporator adopts a horizontal feed method. When the same amount of steam is consumed, the front evaporation device can generate more secondary steam under the horizontal feed method. And under this method, the raw liquid does not need to be equipped with an intermediate water pump for transportation, which can further reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a cross-sectional view of a multi-effect horizontal tube falling film evaporator according to an embodiment;

[0023] Figure 2 is a cross-sectional view of a single evaporation device in a multi-effect horizontal tube falling film evaporator according to an embodiment;

[0024] Figure 3 is a front view of a front tube plate in a multi-effect horizontal tube falling film evaporator according to an embodiment;

[0025] Figure 4 is a front view of a rear tube plate in a multi-effect horizontal tube falling film evaporator according to an embodiment;

[0026] Figure 5 The three-dimensional diagram of the spray device in the multi-effect horizontal tube falling film evaporator according to the embodiment Figure 1 ;

[0027] Figure 6 The three-dimensional diagram of the spray device in the multi-effect horizontal tube falling film evaporator according to the embodiment Figure 2 ;

[0028] Figure 7 1 is a bottom view of a spray device in a multi-effect horizontal tube falling film evaporator according to an embodiment.

[0029] In the figure, 1, front head; 11, steam inlet; 2, rear head; 21, steam outlet; 3, evaporation device; 301, steam inlet chamber; 302, evaporation chamber; 303, exhaust chamber; 31, front tube plate; 311, steam inlet hole; 312, front exhaust hole; 32, rear tube plate; 321, rear exhaust hole; 33, front tube seal; 34, rear tube seal; 35, front drain pipe; 36, rear drain pipe; 37, condensate outlet; 38, liquid outlet; 39, spray pipe outlet; 4, heat exchange tube; 41, upper tube; 42, lower tube; 5, spray device; 50, spray gap; 51, spray mother pipe; 52, spray sub-pipe; 521, spray hole; 61, first pressure detection device; 62, second pressure detection device; 63, temperature detection device; 7, wire mesh demister; 8, bracket. DETAILED DESCRIPTION

[0030] The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like used in the present invention to indicate the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0032] In the description of the present invention, it should be understood that the terms "connected", "connected", "fixed" and the like used in the present invention should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or a welding connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The present invention uses the terms "first", "second", etc. to describe various information, but these information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the "first" information may also be referred to as the "second" information, and similarly, the "second" information may also be referred to as the "first" information.

[0034] With reference to the drawings, in the description of the front and rear directions of the present invention, “front” refers to the left side of the drawings, and “rear” refers to the right side of the drawings.

[0035] Reference Figure 1 and Figure 2 A multi-effect horizontal tube falling film evaporator according to an embodiment of the utility model comprises a front head 1, a rear head 2 and at least two evaporation devices 3; the front head 1, the evaporation device 3 and the rear head 2 are connected in sequence from front to back, the front head 1 is provided with a steam inlet 11, and the rear head 2 is provided with a steam outlet 21; specifically, the steam inlet 11 is located at the top of the front head 1, and is formed by a flange at the upper left top of the first effect; the steam outlet 21 is located at the top of the rear head 2.

[0036] The evaporation device 3 includes a front tube plate 31, a rear tube plate 32, a front tube seal 33, a rear tube seal 34, a front drain pipe 35, a rear drain pipe 36 and a heat exchange tube 4. The front tube plate 31 and the rear tube plate 32 are arranged in a front-to-back interval to divide the interior of the evaporation device 3 from front to back into a steam inlet chamber 301, an evaporation chamber 302 and an exhaust chamber 303. In the two adjacent evaporation devices 3, the exhaust chamber 303 of the first evaporation device 3 is connected to the steam inlet chamber 301 of the second evaporation device 3. Among them, each evaporation device 3 can be called a first effect evaporation device 3, a second effect evaporation device 3, a third effect evaporation device 3, a fourth effect evaporation device 3, and so on from front to back. As shown in the figure, in a specific embodiment of the present application, an evaporator with a three-effect evaporation device 3 is provided.

[0037] The front tube plate 31 is provided with a steam inlet hole 311 and a front steam exhaust hole 312. The front pipe seal 33 is installed on the side of the front tube plate 31 facing the steam inlet chamber 301, and the front pipe seal 33 is connected with the evaporation chamber 302 through the front steam exhaust hole 312 and is connected with the steam inlet chamber 301 through the front liquid discharge pipe 35. The rear pipe seal 34 is installed on the side of the rear tube plate 32 facing the steam exhaust chamber 303, and the rear pipe seal 34 is connected with the steam exhaust chamber 303 through the rear liquid discharge pipe 36. The rear tube plate 32 is provided with a rear steam exhaust hole 321, and the evaporation chamber 302 is connected with the steam exhaust chamber 303 through the rear steam exhaust hole 321.

[0038] The heat exchange tube 4 is arranged in the evaporation chamber 302 and extends in the front-to-back direction. The heat exchange tube 4 includes an upper tube 41 and a lower tube 42. The front end of the lower tube 42 is connected to the front tube plate 31 and communicates with the steam inlet chamber 301 through the steam inlet hole 311. The front end of the upper tube 41 is connected to the front tube plate 31 and communicates with the front tube seal 33. The rear ends of the lower tube 42 and the upper tube 41 are both connected to the rear tube plate 32 and communicate with the rear tube seal 34.

[0039] Specifically, the heat exchange tube 4 is fixedly connected to the front tube sheet 31 and the rear tube sheet 32, and the front tube seal 33 is bolted to the front tube sheet 31, and the rear tube seal 34 is bolted to the rear tube sheet 32. The front tube seal 33 and the rear tube seal 34 are used to divide the heat exchange tube 4 into an upper tube 41 and a lower tube 42. After the steam enters the evaporator, it first passes into the lower tube 42 through the steam inlet hole 311, then enters the upper tube 41 through the rear tube seal 34, and then enters the front tube seal 33. The front tube seal 33 is connected to the evaporation chamber 302 through the front exhaust hole 312, so that the uncondensed steam after passing through the upper tube 41 and the lower tube 42 is passed into the evaporation chamber 302 to mix with the steam generated by the evaporation of the raw material liquid. The rear exhaust hole 321 is used to pass the mixed steam from the evaporation chamber 302 into the exhaust chamber 303, and enter the steam inlet chamber 301 of the next evaporation device 3 for reuse.

[0040] A condensed water outlet 37 is provided at the bottom of the steam inlet chamber 301 , a spray device 5 for spraying liquid is provided at the top of the evaporation chamber 302 , and a liquid outlet 38 is provided at the bottom of the evaporation chamber 302 .

[0041] The wastewater raw liquid of the evaporator of the utility model can enter each evaporation device 3 at the same time for evaporation and concentration; and through the front tube plate 31, the front tube seal 33, the rear tube plate 32 and the rear tube seal 34, the steam generated by the evaporation of the liquid in the front evaporation device 3 and the steam that is not completely condensed after passing through the front evaporation device 3 can be effectively mixed and then passed into the next evaporation device 3, which can reduce the amount of steam used and reduce the amount of condensation during the steam movement process, which not only reduces the risk of scaling, improves the steam utilization rate, but also improves the evaporation efficiency and system performance. This evaporator adopts a horizontal feed method. When the same amount of steam is consumed, the front evaporation device 3 can generate more secondary steam under the horizontal feed method. And under this method, the raw liquid does not need to be transported by an intermediate water pump, which can further reduce energy consumption.

[0042] See also Figure 5 and Figure 6 In some improved solutions of the present application, there is a spray pipe hole at the top of the evaporation chamber 302, and the spray device 5 includes a spray main pipe 51 and a plurality of spray sub-pipes 52 extending in the front-to-back direction. The plurality of spray sub-pipes 52 are arranged at intervals in the left-right direction in the same plane and are arranged above the heat exchange tube 4. The spray main pipe 51 is passed through the spray pipe hole and is connected to each of the spray sub-pipes 52. The spray device 5 adopts a method of leading multiple spray sub-pipes 52 from a spray main pipe 51. The spray device 5 has a simple structure, higher operational stability, and higher equipment operation reliability. As shown in the embodiment shown in the figure, there are 7 spray sub-pipes 52.

[0043] See also Figure 7In some improved solutions of the present application, the bottom of the spray sub-tube 52 is provided with a plurality of spray holes 521 spaced apart in the front-to-back direction, and the spacing between the spray holes 521 is designed to be 15 mm to 25 mm according to the tube surface wavelength formula and the actual flow range. Specifically, in the present embodiment, the spacing between the spray holes 521 is 20 mm.

[0044] See also Figure 3 In some improved solutions of the present application, a spray gap 50 is formed between the spray sub-tube 52 and the heat exchange tube 4, and the front steam exhaust hole 312 is arranged toward the spray gap 50. The front tube seal 33 is connected with the spray gap 50 through the front steam exhaust hole 312, and is connected with the evaporation chamber 302 through the spray gap 50. Excess steam can enter the spray gap 50 through the front steam exhaust hole 312, and then be discharged into the next-effect evaporator together with the steam formed by the feed liquid on the heat exchange tube 4.

[0045] In some improved schemes of the present application, the heat exchange tubes 4 include multiple rows of upper tubes 41 and multiple rows of lower tubes 42, and adjacent upper tubes 41 in the same row are arranged at intervals along the left-right direction, and adjacent lower tubes 42 in the same row are arranged at intervals along the left-right direction. The present application is a horizontal tube falling film evaporator, which has the advantages of high heat transfer efficiency and low fouling. In the specific embodiment, the heat exchange tubes 4 are 7 rows, 3 rows of upper tubes 41, and 4 rows of lower tubes 42.

[0046] In some improved schemes of the present application, the upper tubes 41 in each adjacent row are staggered, and the lower tubes 42 in each adjacent row are staggered. This arrangement allows the raw material liquid on the outer wall of the upper row of heat exchange tubes 4 to drip onto the lower row of heat exchange tubes 4, making the liquid distribution on the outer wall of the heat exchange tubes 4 more uniform.

[0047] In some improved solutions of the present application, a first pressure detection device 61 is further provided in the front sealing head 1 and / or the rear sealing head 2. Specifically, both the front sealing pipe and the rear sealing pipe are provided with a pressure measuring point for connecting the first pressure detection device 61, so as to realize the monitoring and control of the steam in the whole circulation process.

[0048] In some improved solutions of the present application, a second pressure detection device 62 and / or a temperature detection device 63 are further provided in the evaporation device 3, so as to monitor and control the pressure and temperature in the evaporation chamber 302. Specifically, instrument interfaces for connecting the second pressure detection device 62 and the temperature detection device 63 are respectively provided at the upper end of the evaporation device 3.

[0049] See also Figure 4In some improved schemes of the present application, the evaporation device 3 also includes a wire mesh demister 7 for intercepting salt water mist, and the wire mesh demister 7 is arranged on the rear exhaust port 321. Since steam is generated during the evaporation of the raw material liquid, as the raw material liquid evaporates, some of the raw material liquid will be atomized into small droplets and flow with the steam, and the droplets will merge into the water vapor. If the droplets are not removed in time, they may cause corrosion to the pipe wall. Therefore, defoaming technology is required to remove these droplets. Using the wire mesh demister 7, the salt water mist entrained in the water vapor will be intercepted when it hits the wire mesh demister 7, forming tiny droplets, and then aggregated into larger droplets and dripping down, thereby improving the heat transfer efficiency of the equipment.

[0050] In some improved solutions of the present application, the outer bottom of the evaporation device 3 is also provided with a bracket 8 for lifting it in the air, so that the condensed water outlet 37 and the liquid outlet 38 are suspended in the air for connecting them to the pipeline. The front head 1, the rear head 2 and each evaporation device 3 of the present application are connected by flanges, and a sealing gasket is provided to achieve sealing, thereby reducing the amount of steam used, improving the evaporation efficiency, and increasing the heat transfer coefficient of the multiple-effect evaporator, thereby improving the heat transfer performance of the system and reducing the potential risk of clogging and scaling.

[0051] The specific use process of the specific embodiment of the utility model is:

[0052] Steam enters the steam inlet chamber 301 from the steam inlet 11 of the front end 1, and enters the lower tube 42 of the heat exchange tube 4 through the steam inlet hole 311 to condense. A part of the condensed water enters the steam inlet chamber 301 from the front end of the heat exchange tube 4, flows out through the condensed water outlet 37, and a part of it flows into and fills the rear tube seal 34. The rear tube seal 34 is connected to a rear drain pipe 36 with a U-shaped tube design. The U-shaped rear drain pipe 36 can play a role in sealing gas after being filled with condensed water. At the same time, due to the pressure difference, the condensed water flows out from the condensed water outlet 37. The uncondensed steam enters the upper tube 41 of the heat exchange tube 4 through the rear end of the upper tube 41 in the rear tube seal 34. The condensed water formed by the upper tube 41 flows into the front tube seal 33, which is also connected to the front liquid discharge pipe 35 of U-shaped tube design. After being filled with condensed water, the U-shaped tube also has the function of sealing the steam. The uncondensed steam in the front tube seal 33 will enter the evaporation chamber 302 through the front exhaust hole of the front tube plate 31, and then, together with the secondary steam generated by the evaporation of the raw material liquid, it will serve as a heat source and enter the exhaust chamber 303 through the rear exhaust hole 321 on the rear tube plate 32, and then pass into the next-effect evaporation device 3.

[0053] A spray device 5 is provided at the upper end of the evaporation chamber 302, and a spray main pipe 51 thereof is provided with a spray pipe hole and is sealed by a seal. The raw material liquid passes through the spray main pipe 51 and the spray sub-pipe 52 to evenly distribute the raw material liquid to the outer wall of each heat exchange tube 4 and form a liquid film. The liquid film forms a falling film flow along the outer wall of the tube under the action of gravity. During the falling film process, the liquid film absorbs heat and evaporates to generate steam, and the unevaporated raw material liquid flows out from the lower end raw material liquid outlet 38.

[0054] In summary, the embodiment of the utility model provides a multi-effect horizontal tube falling film evaporator, which has the following advantages:

[0055] 1. Each evaporation device 3 is provided with a front tube seal 33 and a rear tube seal 34, which divide the heat exchange tube 4 into an upper tube 41 and a lower tube 42. A front steam discharge hole 312 is opened on the upper part of the front tube plate 31, so that the uncondensed steam enters the evaporation chamber 302 and mixes with the steam generated by the evaporation of the raw liquid, which can effectively reduce the use of steam, improve the steam utilization rate, and thus improve the evaporation efficiency and system performance.

[0056] 2. A triangular rear steam exhaust hole 321 is provided on each rear tube plate 32. Through the communication between the steam exhaust chamber 303 and the steam inlet chamber 301 between each evaporation device 3, the rear steam exhaust hole 321 is used to allow the mixed steam to quickly and smoothly enter the next-effect evaporation device 3, which can reduce the risk of scaling, reduce the condensation amount during the steam movement process, and improve the steam utilization rate.

[0057] 3. Design the spray device 5 so that it is in the form of a spray main pipe 51 connected to multiple spray sub-pipes 52, and a horizontal tube falling film evaporator is formed in combination with multiple rows of heat exchange tubes 4. The overall structure is simple, the operation stability is higher, the equipment operation reliability is higher, and the liquid distribution on the outer wall of the heat exchange tube 4 is more uniform. This evaporation method has the advantages of high heat transfer efficiency and low scaling.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principle of the present invention. These improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A multi-effect horizontal tube falling film evaporator, characterized in that: It comprises a front head (1), a rear head (2) and at least two evaporation devices (3); the front head (1), the at least two evaporation devices (3) and the rear head (2) are connected in sequence from front to back; the front head (1) is provided with a steam inlet (11), and the rear head (2) is provided with a steam outlet (21); The evaporator (3) comprises a front tube plate (31), a rear tube plate (32), a front tube seal (33), a rear tube seal (34), a front drain pipe (35), a rear drain pipe (36) and a heat exchange tube (4); the front tube plate (31) and the rear tube plate (32) are arranged in a front-to-back spacing so as to divide the interior of the evaporator (3) from front to back into a steam inlet chamber (301), an evaporation chamber (302) and a steam exhaust chamber (303); in two evaporators (3) adjacent to each other, the steam exhaust chamber (303) of the front evaporator (3) is connected to the steam inlet chamber (301) of the rear evaporator (3); The front tube plate (31) is provided with a steam inlet hole (311) and a front steam exhaust hole (312); the front tube seal (33) is installed on a side of the front tube plate (31) facing the steam inlet chamber (301); the front tube seal (33) is connected to the evaporation chamber (302) through the front steam exhaust hole (312) and is connected to the steam inlet chamber (301) through the front liquid discharge pipe (35); the rear tube seal (34) is installed on a side of the rear tube plate (32) facing the steam exhaust chamber (303); the rear tube seal (34) is connected to the steam exhaust chamber (303) through the rear liquid discharge pipe (36); the rear tube plate (32) is provided with a rear steam exhaust hole (321); the evaporation chamber (302) is connected to the steam exhaust chamber (303) through the rear steam exhaust hole (321); The heat exchange tube (4) is arranged in the evaporation chamber (302) extending in the front-to-back direction, and comprises an upper tube (41) and a lower tube (42); the front end of the lower tube (42) is connected to the front tube plate (31) and communicates with the steam inlet chamber (301) through the steam inlet hole (311); the front end of the upper tube (41) is connected to the front tube plate (31) and communicates with the front tube seal (33); the rear ends of the lower tube (42) and the upper tube (41) are both connected to the rear tube plate (32) and communicate with the rear tube seal (34); The bottom of the steam inlet chamber (301) is provided with a condensed water outlet (37), the top of the evaporation chamber (302) is provided with a spray device (5) for spraying liquid, and the bottom of the evaporation chamber (302) is provided with a liquid outlet (38).

2. The multi-effect horizontal tube falling film evaporator according to claim 1, characterized in that: A spray pipe hole is provided at the top of the evaporation chamber (302); the spray device (5) comprises a spray main pipe (51) and a plurality of spray sub-pipes (52) extending in the front-to-back direction; the plurality of spray sub-pipes (52) are arranged at intervals in the left-to-right direction in the same plane and are arranged above the heat exchange tube (4); the spray main pipe (51) is passed through the spray pipe hole and is respectively connected to each of the spray sub-pipes (52).

3. The multi-effect horizontal tube falling film evaporator according to claim 2, characterized in that: The bottom of the spray sub-tube (52) is provided with a plurality of spray holes (521) spaced apart in the front-to-back direction, and the spacing between two adjacent spray holes (521) is 15 mm to 25 mm.

4. The multi-effect horizontal tube falling film evaporator according to claim 2, characterized in that: A spray gap (50) is formed between the spray sub-tube (52) and the heat exchange tube (4), and the front steam exhaust hole (312) is arranged toward the spray gap (50).

5. The multi-effect horizontal tube falling film evaporator according to claim 1, characterized in that: The heat exchange tubes (4) include multiple rows of upper tubes (41) and multiple rows of lower tubes (42), wherein adjacent upper tubes (41) in the same row are arranged at intervals along the left-right direction, and adjacent lower tubes (42) in the same row are arranged at intervals along the left-right direction.

6. The multi-effect horizontal tube falling film evaporator according to claim 5, characterized in that: The upper tubes (41) in each row adjacent to each other are arranged in a staggered manner, and the lower tubes (42) in each row adjacent to each other are arranged in a staggered manner.

7. The multi-effect horizontal tube falling film evaporator according to claim 1, characterized in that: A first pressure detection device (61) is also provided in the front sealing head (1) and / or in the rear sealing head (2).

8. The multi-effect horizontal tube falling film evaporator according to claim 1, characterized in that: The evaporation device (3) is also provided with a second pressure detection device (62) and / or a temperature detection device (63).

9. The multi-effect horizontal tube falling film evaporator according to claim 1, characterized in that: The evaporation device (3) further comprises a wire mesh demister (7) for intercepting salt water mist, and the wire mesh demister (7) is arranged on the rear exhaust hole (321).

10. The multi-effect horizontal tube falling film evaporator according to any one of claims 1 to 9, characterized in that: The outer bottom of the evaporation device (3) is also provided with a bracket (8) for lifting it in mid-air.

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