A sewage multi-stage screening MVR evaporator

Abstract

The present invention discloses a sewage multi-stage screening MVR evaporator, which relates to the technical field of sewage treatment, and includes an evaporation bin, the evaporation bin is fixedly connected with a connecting frame, the side of the evaporation bin close to the connecting frame is connected with a return pipe, the connecting frame is fixedly connected with a separation bin, the top of the evaporation bin is connected with a first guide pipe, the side of the evaporation bin close to the first guide pipe is provided with a liquid inlet, the upper part of the evaporation bin is fixedly connected with a coarse falling film heat exchange tube, and the coarse falling film heat exchange tube is fixedly connected with a plurality of fine falling film heat exchange tubes. On the basis of the existing multiple fine falling film heat exchange tubes, the present invention reduces the possibility of solid particles or other impurities accumulating in the fine falling film heat exchange tubes and causing blockage by adding a coarse falling film heat exchange tube, and even if the fine falling film heat exchange tube is blocked, the sewage can still be continuously heated and flowed through the coarse falling film heat exchange tube, thereby ensuring that the system can continue to operate and reducing the downtime caused by local failures.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a sewage multi-stage screening MVR evaporator. Background Art

[0002] MVR evaporator, full name Mechanical Vapor Recompression evaporator, is a highly efficient and energy-saving evaporation equipment. It uses the secondary steam generated by itself as a heating source after being pressurized and heated by a compressor to achieve the evaporation and concentration process of the solution. It has the advantages of low energy consumption and low operating cost, and has been widely used in wastewater treatment and other fields.

[0003] At present, the common MVR evaporator is usually divided into four stages: preheating, evaporation, circulation and separation. In the evaporation stage, the fluid is mostly used to form a thin film flow along the tube wall of multiple falling film heat exchange tubes under the action of gravity to achieve evaporation and concentration of wastewater. This is because multiple thin falling film heat exchange tubes can better form a uniform film flow, increase the heat transfer area, and improve the heat transfer efficiency. At the same time, the fluid in the thin tube is more likely to form a uniform film, thereby better ensuring the uniform distribution of the fluid, avoiding local overheating or uneven heat transfer, and increasing the evaporation rate, thereby achieving efficient heat transfer and evaporation. However, the diameter of the thin tube is small, and when solid particles or impurities in the wastewater accumulate, it is easy to clog, thereby affecting the evaporation efficiency.

[0004] Based on the above reasons, the present invention proposes a sewage multi-stage screening MVR evaporator. Summary of the invention

[0005] In order to overcome the disadvantage that the capillary tubes are small in diameter and easily blocked, the present invention provides a sewage multi-stage screening MVR evaporator.

[0006] A sewage multi-stage screening MVR evaporator, comprising an evaporation bin, the evaporation bin is fixedly connected to a connecting frame, a side of the evaporation bin close to the connecting frame is connected to a return pipe, the connecting frame is fixedly connected to a separation bin, the separation bin is fixedly connected to a steam compressor, the return pipe is connected to the steam compressor, the top of the evaporation bin is connected to a first guide pipe, a side of the evaporation bin close to the first guide pipe is provided with a liquid inlet, a coarse falling film heat exchange tube is fixedly connected to the upper part of the evaporation bin, a distribution plate is fixedly connected to the upper part of the evaporation bin, a plurality of distribution holes are provided on the distribution plate, the distribution plate is located above the coarse falling film heat exchange tube, a side of the evaporation bin close to the first guide pipe and the liquid inlet is set as a recovery channel, a return frame is fixedly connected to the middle of the evaporation bin, the return frame and the recovery channel are both connected Towards the first guide pipe, the reflux rack passes through the interior of the rough falling film heat exchange tube, the lower part of the reflux rack is set to be conical and has a plurality of through holes, the conical outer side surface guides the steam flowing out of the rough falling film heat exchange tube into the evaporation bin, the evaporation bin is connected with a steam pipe, the rough falling film heat exchange tube is fixedly connected with a plurality of fine falling film heat exchange tubes, the bottom ends of the fine falling film heat exchange tubes pass through the corresponding through holes in the lower part of the reflux rack, the conical inner side surface gathers the steam flowing out of the fine falling film heat exchange tubes and guides them into the reflux rack, the evaporation bin is fixedly connected with an evaporation rack, the top of the evaporation rack is set to be open, the lower part of the reflux rack is located in the evaporation rack, the gap between the inside of the evaporation bin and the evaporation rack is set as an air guide channel, and the gap between the rough falling film heat exchange tube and the reflux rack is set as a heating channel.

[0007] Optionally, the evaporation rack has two upper and lower cavities.

[0008] Optionally, at least one first liquid outlet is formed in the cavity on the upper side of the evaporation rack, and a second liquid outlet is formed in the cavity on the lower side of the evaporation rack.

[0009] Optionally, at least one second flow guide tube is further included, and the second flow guide tube is communicated with the cavity at the lower side of the evaporation rack.

[0010] Optionally, a first acceleration ring is further included, wherein the first acceleration ring is fixedly connected to a side of the return pipe close to the steam compressor.

[0011] Optionally, it also includes a first guide paddle, which is rotatably connected to one end of the first guide pipe close to the return pipe, and the blades of the first guide paddle penetrate into the return pipe. The end of the first guide paddle away from the return pipe is fixedly connected to a second guide paddle, and the end of the second guide paddle away from the return pipe is fixedly connected to a third guide paddle, the third guide paddle is rotatably connected to the first guide pipe, and the second guide paddle and the third guide paddle are both located in the first guide pipe.

[0012] Optionally, the pipeline at the inlet of the first guide pipe is configured as a double channel, and the third guide paddle is located between the double channels of the first guide pipe.

[0013] Optionally, a second acceleration ring is further included, and the second acceleration ring is fixedly connected to a side of the second guide paddle close to the third guide paddle.

[0014] Optionally, a liquid inlet pipe is further included, the liquid inlet pipe is fixedly connected to a side of the evaporation bin close to the rough falling film heat exchange tube, the liquid inlet pipe passes through the liquid inlet port, and the liquid inlet pipe is fixedly connected to a solenoid valve.

[0015] Optionally, a heating pipe is further included, and the heating pipe is fixedly connected to a side of the reflux pipe close to the evaporation bin.

[0016] Beneficial effects:

[0017] The present invention increases the number of existing thin falling film heat exchange tubes by providing thick falling film heat exchange tubes, thereby reducing the possibility of solid particles or other impurities accumulating in the thin falling film heat exchange tubes and causing blockage. Even if the thin falling film heat exchange tubes are blocked, the sewage can still be continuously heated and flow through the thick falling film heat exchange tubes, thereby ensuring the continuous operation of the system and reducing the downtime caused by local failures.

[0018] The present invention adds a reflux rack so that the thin film sewage on the coarse falling film heat exchange tube is not only externally heated by the steam in the evaporation bin, but also internally heated by the steam in the reflux rack. The double internal and external heating makes the sewage in the coarse falling film heat exchange tube evaporate faster, thereby improving the evaporation efficiency of the sewage.

[0019] The present invention arranges the conical inner and outer surfaces of the lower part of the reflux rack so that the steam from the reflux rack and the thin falling film heat exchange tube is diverted into the first guide tube, thereby accelerating the upward floating speed of the steam and avoiding local accumulation of the steam.

[0020] The present invention increases the evaporation rack and the second guide pipe, so that the wastewater is subjected to multi-stage evaporation and screening, thereby improving the purity of the wastewater concentrate.

[0021] The present invention accelerates the steam in the left part of the first guide pipe to flow rightward to the middle through the third guide paddle and the second acceleration ring, accelerates the steam in the middle part of the first guide pipe to flow rightward to the right through the blades on the left part of the second guide paddle, and accelerates the steam in the right part of the first guide pipe to flow downward to the separation bin through the blades on the right part of the second guide paddle. In this way, the steam in the first guide pipe is quickly discharged to avoid the accumulation of steam in the first guide pipe.

[0022] The present invention compensates for the heat lost in the secondary steam transmission process through the heating pipe, thereby preventing the secondary steam from entering the evaporation bin without sufficient heat to heat the sewage film. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0024] Figure 2 It is a three-dimensional structural cross-sectional view of the present invention.

[0025] Figure 3 It is a three-dimensional structural schematic diagram of the evaporation chamber, reflux rack and evaporation rack of the present invention.

[0026] Figure 4 It is a schematic diagram of the three-dimensional structure of the coarse falling film heat exchange tube, the reflux rack and the fine falling film heat exchange tube of the present invention.

[0027] Figure 5 It is a schematic diagram of the three-dimensional structure of the evaporation rack and the second guide tube of the present invention.

[0028] Figure 6 It is a schematic diagram of the three-dimensional structure of the first acceleration ring, the second acceleration ring and other components of the present invention.

[0029] Figure 7 It is a sectional view of the three-dimensional structure of the second acceleration ring of the present invention.

[0030] Figure 8 It is a schematic diagram of the three-dimensional structure of the first guide paddle, the second guide paddle and the third guide paddle of the present invention.

[0031] Fig. 9 It is a three-dimensional structural schematic diagram of the evaporation chamber, liquid inlet pipe, solenoid valve and other components of the present invention.

[0032] Fig.10 It is a three-dimensional structural schematic diagram of components such as the return pipe and the heating pipe of the present invention.

[0033] The markings of the components in the accompanying drawings are as follows: 101: evaporation chamber, 102: connecting frame, 103: reflux pipe, 104: steam compressor, 105: separation chamber, 106: first guide pipe, 107: liquid inlet, 108: coarse falling film heat exchange tube, 1081: distribution plate, 1082: recovery channel, 109: reflux frame, 1091: steam pipe, 110: fine falling film heat exchange tube, 111: evaporation frame, 112: first liquid outlet, 113: second liquid outlet, 114: air guide channel, 115: heating channel, 201: second guide pipe, 301: first acceleration ring, 302: first guide paddle, 303: second guide paddle, 304: third guide paddle, 305: second acceleration ring, 401: liquid inlet pipe, 402: solenoid valve, 501: heating pipe. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0035] Example 1: A sewage multi-stage screening MVR evaporator, combined with the attached Figure 1 To Attachment Figure 4, including an evaporation bin 101, the bottom of the evaporation bin 101 is provided with an outlet connected to a downstream device, a connecting frame 102 is fixedly connected to the right side of the evaporation bin 101, a return pipe 103 is connected to the lower right side of the evaporation bin 101, a separation bin 105 is fixedly connected to the upper part of the connecting frame 102, a steam compressor 104 is fixedly connected to the top of the separation bin 105, the top of the return pipe 103 is connected to the steam compressor 104, a first guide pipe 106 is connected to the top of the evaporation bin 101, the right end of the first guide pipe 106 is connected to the separation bin 105, a liquid inlet 107 for sewage feeding is provided on the left side of the top of the evaporation bin 101, and the evaporation bin 105 is connected to the upper part of the connecting frame 102. A rough falling film heat exchange tube 108 is fixedly connected to the upper part of the evaporation chamber 101, and a distribution plate 1081 is fixedly connected to the upper part of the evaporation chamber 101. The sewage flowing in through the liquid inlet 107 flows to the distribution plate 1081. The distribution plate 1081 has a plurality of distribution holes for evenly distributing the sewage. The distribution plate 1081 is located above the rough falling film heat exchange tube 108. A side of the evaporation chamber 101 close to the first guide pipe 106 and the liquid inlet 107 is set as a recovery channel 1082. A reflux rack 109 is fixedly connected to the middle of the evaporation chamber 101. The reflux rack 109 and the recovery channel 1082 both lead to the first guide pipe 106. The reflux rack 109 is connected to the rough falling film heat exchange tube 108. The film heat exchange tube 108 passes through the inside, and the lower part of the reflux rack 109 is set to be conical and has multiple through holes. The outer side of the cone guides the steam flowing out of the coarse falling film heat exchange tube 108 into the evaporation bin 101. The left side of the evaporation bin 101 is connected with a steam pipe 1091 for introducing an external steam source. A plurality of fine falling film heat exchange tubes 110 are fixedly connected to the upper part of the coarse falling film heat exchange tube 108. The bottom ends of the fine falling film heat exchange tubes 110 pass through the corresponding through holes at the lower part of the reflux rack 109. The inner side of the cone gathers the steam flowing out of the fine falling film heat exchange tubes 110 and guides it into the reflux rack 109. The lower side of the evaporation bin 101 is fixedly connected with an evaporation rack 111. The top of the evaporation rack 111 is set to be open, and the lower part of the reflux rack 109 is located inside the evaporation rack 111. The evaporation rack 111 has two upper and lower cavities for extending the flow time of the concentrated liquid, thereby extending the evaporation process. A plurality of first liquid outlets 112 are provided at the bottom of the cavity on the upper side of the evaporation rack 111. The cavity on the lower side of the evaporation rack 111 is divided into an upper and lower part. A second liquid outlet 113 is provided between the upper and lower parts of the cavity on the lower side of the evaporation rack 111. The gap between the inside of the evaporation bin 101 and the evaporation rack 111 is set as an air guide channel 114, and the gap between the coarse falling film heat exchange tube 108 and the reflux rack 109 is set as a heating channel 115.

[0036] Combined with Figure 2 , Attachment Figure 3 and attached Figure 5 , further comprising a plurality of second flow guide tubes 201 , the second flow guide tubes 201 being communicated with the bottom of the cavity at the lower side of the evaporation rack 111 .

[0037] The MVR evaporator can be used to evaporate and concentrate sewage. In the startup stage, an external steam source is introduced into the evaporation chamber 101 through the steam pipe 1091, so that the entire evaporation chamber 101 is filled with steam. The steam heats the coarse falling film heat exchange tube 108, the reflux rack 109, the fine falling film heat exchange tube 110, the evaporation rack 111 and the second guide tube 201. Subsequently, the sewage to be screened is passed through the liquid inlet 107 into the top of the distribution plate 1081, and the sewage is diverted through the distribution holes of the distribution plate 1081, so that a part of the sewage is evenly distributed to each fine falling film heat exchange tube. 110, and another part of the sewage is introduced into the coarse falling film heat exchange tube 108. Under the action of gravity, the sewage flows in a uniform film along the inner wall of the coarse falling film heat exchange tube 108 and each fine falling film heat exchange tube 110. During the downward flow, the film-like sewage exchanges heat with the steam in the evaporation bin 101 through each tube wall. During the heating process, part of the water in the coarse falling film heat exchange tube 108 and each fine falling film heat exchange tube 110 evaporates rapidly to generate steam. Since the film-like sewage flows at a fast speed and the liquid film is thin, the generated steam will be entrained by the liquid film and thus flow downward with the liquid film.

[0038] The wastewater after evaporation and dehydration in the fine falling film heat exchange tube 110 is concentrated and flows downward into the upper cavity of the evaporation rack 111, and the entrained steam also flows directly into the upper cavity of the evaporation rack 111. Then, the steam in the upper cavity of the evaporation rack 111 floats upward due to its light weight. Affected by the structure of the conical inner surface of the lower part of the return rack 109, the steam coming out of the fine falling film heat exchange tube 110 is guided to flow to the upper part of the return rack 109, and then enters the first guide pipe 106. The steam heats the inner wall of the return rack 109 during the above-mentioned upward floating process. The heat of the steam in the return rack 109 is transferred to the inner wall of the coarse falling film heat exchange tube 108 through the heating channel 115. In this way, the thin film wastewater on the coarse falling film heat exchange tube 108 is not only externally heated by the steam in the evaporation bin 101, but also internally heated by the steam in the return rack 109.

[0039] The wastewater after evaporation and dehydration in the coarse falling film heat exchange tube 108 is concentrated and guided into the upper cavity of the evaporation frame 111 along the tapered outer side surface of the lower part of the downward return frame 109, and the entrained steam also directly flows into the upper cavity of the evaporation frame 111. Then, the steam in the upper cavity of the evaporation frame 111 floats upward due to its light weight. Affected by the structure of the tapered outer side surface of the lower part of the return frame 109, the steam coming out of the coarse falling film heat exchange tube 108 is guided to float upward along the inner wall of the evaporation frame 111 into the evaporation bin 101, and finally floats into the first guide pipe 106 through the recovery channel 1082;

[0040] The steam entering the first guide pipe 106 flows into the separation chamber 105, and the separation chamber 105 further separates the steam inside. The separated liquid is stored in the separation chamber 105, and the remaining steam that is not completely separated continues to rise and enters the return pipe 103. After compression and heating by the steam compressor 104, the steam after secondary heating is transported to the bottom of the evaporation chamber 101 through the return pipe 103. The steam entering the bottom of the evaporation chamber 101 finally completely permeates the entire evaporation chamber 101 through the air guide channel 114. At this time, the secondary steam can be used as a heating source medium for the next batch of sewage, thereby realizing a heat cycle.

[0041] The steam after secondary heating will heat the evaporation rack 111 and the second guide tube 201, and further evaporate and heat the concentrated liquid on the evaporation rack 111. Then, the concentrated liquid in the upper cavity of the evaporation rack 111 slowly flows into the upper part of the lower cavity of the evaporation rack 111 through the first liquid outlet 112 for secondary evaporation, and the concentrated liquid in the upper part of the lower cavity of the evaporation rack 111 slowly flows into the lower part of the lower cavity of the evaporation rack 111 through the second liquid outlet 113 for tertiary evaporation, wherein the generated steam is discharged upward into the evaporation bin 101 through the first liquid outlet 112, and then the steam is separated through the separation bin 105, and the final concentrated liquid passes through the second guide tube 201, and the concentrated liquid after multi-stage evaporation is discharged to the bottom of the evaporation bin 101, and finally the concentrated liquid after multi-stage evaporation is completely discharged to the downstream equipment through the outlet at the bottom of the evaporation bin 101.

[0042] In summary, the present invention, on the basis of the existing multiple fine falling film heat exchange tubes 110, increases the provision of coarse falling film heat exchange tubes 108, thereby reducing the possibility of solid particles or other impurities accumulating in the fine falling film heat exchange tubes 110 and causing blockage. Even if the fine falling film heat exchange tubes 110 are blocked, the sewage can still be continuously heated and flowed through the coarse falling film heat exchange tubes 108, thereby ensuring the continuous operation of the system and reducing the downtime caused by local failures.

[0043] The present invention adds a reflux rack 109 so that the thin film wastewater on the coarse falling film heat exchange tube 108 is not only externally heated by the steam in the evaporation bin 101, but also internally heated by the steam in the reflux rack 109. The dual internal and external heating makes the wastewater in the coarse falling film heat exchange tube 108 evaporate faster, thereby improving the evaporation efficiency of the wastewater.

[0044] The present invention uses the structural arrangement of the conical inner and outer surfaces at the bottom of the reflow rack 109 to divert the steam from the reflow rack 109 and the thin falling film heat exchange tube 110 into the first guide tube 106, thereby accelerating the upward floating speed of the steam and avoiding local accumulation of the steam.

[0045] The present invention increases the evaporation rack 111 and the second guide pipe 201, so that the wastewater is subjected to multi-stage evaporation and screening, thereby improving the purity of the wastewater concentrate.

[0046] Embodiment 2: Based on embodiment 1, Figure 6 To Attachment Figure 8 , further comprising a first acceleration ring 301, the first acceleration ring 301 is fixedly connected to one side of the return pipe 103 near the steam compressor 104, the aperture of the first acceleration ring 301 gradually decreases from bottom to top, the right end of the first guide pipe 106 is rotatably connected to the first guide paddle 302, the blades of the first guide paddle 302 penetrate into the return pipe 103, the left end of the rotating rod of the first guide paddle 302 is fixedly connected to the second guide paddle 303, the left end of the rotating rod of the second guide paddle 303 is fixedly connected to the third guide paddle 304, the third guide paddle 304 is rotatably connected to the first guide pipe 106, the second guide paddle 303 and the third guide paddle 304 Both are located in the first guide pipe 106, the blade of the second guide paddle 303 consists of two parts, the blade structure of the left blade of the second guide paddle 303 and the blade structure of the third guide paddle 304 are both set as curved surfaces, the blade structure of the right blade of the second guide paddle 303 and the blade structure of the first guide paddle 302 are both set as planes, the pipeline at the entrance of the first guide pipe 106 is set as a double channel, the third guide paddle 304 is located between the double channels of the first guide pipe 106, and a second acceleration ring 305 is fixedly connected to the left side of the rotating rod of the second guide paddle 303, and the aperture of the second acceleration ring 305 gradually decreases from left to right.

[0047] In order to avoid steam accumulation in the first guide pipe 106, it is necessary to accelerate the rapid discharge of steam in the first guide pipe 106, which is specifically performed as follows: the aperture of the first acceleration ring 301 is set to gradually decrease from bottom to top, accelerating the steam in the return pipe 103 to flow to the blades of the first guide paddle 302, and under the push of the airflow, the first guide paddle 302 drives the second guide paddle 303 to rotate, thereby driving the third guide paddle 304 to rotate, so that the third guide paddle 304 accelerates the steam on the left side of the first guide pipe 106 to flow right to the middle, and the aperture of the second acceleration ring 305 is set to gradually decrease from left to right, further accelerating the steam on the left side of the first guide pipe 106 to flow right to the middle, the blade on the left side of the second guide paddle 303 accelerates the steam in the middle of the first guide pipe 106 to flow right to the right, and the blade on the right side of the second guide paddle 303 accelerates the steam on the right side of the first guide pipe 106 to flow downward to the separation chamber 105.

[0048] Embodiment 3: Based on Embodiment 2, Fig. 9, and also includes a liquid inlet pipe 401, which is fixedly connected to a side of the evaporation bin 101 close to the coarse falling film heat exchange tube 108, and passes through the liquid inlet port 107. The sewage to be treated is fed to the top of the distribution plate 1081 through the liquid inlet pipe 401. The liquid inlet pipe 401 is fixedly connected to the electromagnetic valve 402, and the opening and closing of the liquid inlet pipe 401 are controlled by the electromagnetic valve 402, so as to control the feed amount of sewage and prevent the sewage entering from exceeding the maximum threshold of the evaporation treatment.

[0049] Embodiment 4: Based on Embodiment 3, Fig.10 , and also includes a heating pipe 501, which is fixedly connected to the side of the return pipe 103 close to the evaporation bin 101. The heating pipe 501 compensates for the heat lost during the secondary steam transmission process to prevent the secondary steam from entering the evaporation bin 101 and not having enough heat to heat the sewage film.

[0050] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, all equivalent changes made to the contents described in the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A sewage multi-stage screening MVR evaporator, comprising an evaporation chamber (101), the evaporation chamber (101) being fixedly connected to a connecting frame (102), a side of the evaporation chamber (101) close to the connecting frame (102) being connected to a return pipe (103), the connecting frame (102) being fixedly connected to a separation chamber (105), the separation chamber (105) being fixedly connected to a steam compressor (104), the return pipe (103) being connected to the steam compressor (104), a top of the evaporation chamber (101) being connected to a first guide pipe (106), and a liquid inlet (107) being provided on a side of the evaporation chamber (101) close to the first guide pipe (106), characterized in that: A coarse falling film heat exchange tube (108) is fixedly connected to the upper inner portion of the evaporation bin (101); a distribution plate (1081) is fixedly connected to the upper inner portion of the evaporation bin (101); the distribution plate (1081) has a plurality of distribution holes; the distribution plate (1081) is located above the coarse falling film heat exchange tube (108); and a side of the evaporation bin (101) close to the first flow guide tube (106) and the liquid inlet (107) is provided with a recovery channel ( 1082), a reflux rack (109) is fixedly connected in the middle of the evaporation bin (101), the reflux rack (109) and the recovery channel (1082) both lead to the first guide pipe (106), the reflux rack (109) passes through the inside of the rough falling film heat exchange tube (108), the lower part of the reflux rack (109) is configured to be conical and has a plurality of through holes, the outer side of the conical surface guides the liquid out of the rough falling film heat exchange tube (108) The steam is directed into the evaporation bin (101), the evaporation bin (101) is connected to a steam pipe (1091), the coarse falling film heat exchange tube (108) is fixedly connected to a plurality of fine falling film heat exchange tubes (110), the bottom ends of the fine falling film heat exchange tubes (110) penetrate into corresponding through holes at the bottom of the reflow rack (109), and the conical inner side surfaces gather the steam flowing out of the fine falling film heat exchange tubes (110) and direct it into the reflow rack (109), the evaporation bin (101) is fixedly connected to an evaporation rack (111), the top of the evaporation rack (111) is arranged to be open, the bottom of the reflow rack (109) is located in the evaporation rack (111), the gap between the inside of the evaporation bin (101) and the evaporation rack (111) is arranged to be an air guide channel (114), and the gap between the coarse falling film heat exchange tube (108) and the reflow rack (109) is arranged to be a heating channel (115); It also includes a first acceleration ring (301), the first acceleration ring (301) being fixedly connected to a side of the return pipe (103) close to the steam compressor (104); It also includes a first guide paddle (302), the first guide paddle (302) being rotatably connected to one end of the first guide pipe (106) close to the return pipe (103), a blade of the first guide paddle (302) penetrating into the return pipe (103), a second guide paddle (303) being fixedly connected to one end of the first guide paddle (302) away from the return pipe (103), a third guide paddle (304) being fixedly connected to one end of the second guide paddle (303) away from the return pipe (103), the third guide paddle (304) being rotatably connected to the first guide pipe (106), and both the second guide paddle (303) and the third guide paddle (304) being located in the first guide pipe (106); The pipeline at the inlet of the first flow guide pipe (106) is configured as a double channel, and the third flow guide paddle (304) is located between the double channels of the first flow guide pipe (106).

2. A sewage multi-stage screening MVR evaporator according to claim 1, characterized in that: The evaporation rack (111) is provided with two upper and lower cavities.

3. A sewage multi-stage screening MVR evaporator according to claim 2, characterized in that: At least one first liquid outlet (112) is provided in the cavity on the upper side of the evaporation frame (111), and a second liquid outlet (113) is provided inside the cavity on the lower side of the evaporation frame (111).

4. A sewage multi-stage screening MVR evaporator according to claim 3, characterized in that: It also comprises at least one second flow guide tube (201), wherein the second flow guide tube (201) is in communication with the cavity at the lower side of the evaporation rack (111).

5. A sewage multi-stage screening MVR evaporator according to claim 4, characterized in that: It also includes a second acceleration ring (305), wherein the second acceleration ring (305) is fixedly connected to a side of the second guide paddle (303) close to the third guide paddle (304).

6. A sewage multi-stage screening MVR evaporator according to claim 5, characterized in that: It also includes a liquid inlet pipe (401), the liquid inlet pipe (401) being fixedly connected to a side of the evaporation bin (101) close to the coarse falling film heat exchange tube (108), the liquid inlet pipe (401) passing through the liquid inlet port (107), and the liquid inlet pipe (401) being fixedly connected to a solenoid valve (402).

7. A sewage multi-stage screening MVR evaporator according to claim 6, characterized in that: It also includes a heating pipe (501), wherein the heating pipe (501) is fixedly connected to a side of the return pipe (103) close to the evaporation bin (101).

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