Anti-blocking falling film evaporation device for pulp black liquor evaporation concentration

Abstract

The application discloses a black liquor evaporation and concentration anti-blocking falling film evaporation device applied to the field of evaporation and concentration, and relates to the pulp-making field.The linkage assembly drives the micro-motion tube to reciprocate horizontally and slightly, shear force is generated near the wall surface to destroy the boundary layer, and the liquid film is prevented from being dry-wall scaling due to the increase of viscosity.Compared with the spiral angle structure or steel wire spiral scraping scheme in the prior art, the embodiment does not depend on the improvement of the flow channel structure, does not generate friction and wear with the pipe wall, and completes the anti-scaling by using the running state of the evaporator, so that the structure is simple and reliable.The outer micro-motion tube is arranged as an independent self-rotation area on the linkage sleeve plate, the outer heat exchange tube is driven by the outer fixed ring to superimpose self-rotation on the basis of integral rotation (revolution), stronger local disturbance is provided for the outer high-scaling risk area, the insufficient anti-scaling effect of the outer side caused by the uneven revolution amplitude is accurately compensated, and the self-rotation and the revolution work together, so that the uniformization of the full-tube bundle anti-scaling effect is realized.

Description

Technical Field

[0001] This invention relates to the field of evaporation and concentration, and particularly to an anti-clogging falling film evaporator for evaporation and concentration of pulping black liquor. Background Technology

[0002] Falling film evaporators are the core equipment in the evaporation and concentration section of black liquor in pulping and papermaking. They utilize gravity to form a uniform liquid film along the inner wall of the heat exchange tubes, exchanging heat with the steam outside the tubes to achieve water evaporation. During the evaporation and concentration process of pulping black liquor, as water continues to evaporate, the solid content of the black liquor continuously increases, the viscosity increases significantly, and the fluidity of the liquid film deteriorates. In severe cases, the liquid film may even become discontinuous, leading to problems such as dry walls and scaling on the inner wall of the heat exchange tubes. Severe scaling can cause blockage. Scaling not only significantly reduces the heat transfer coefficient and increases energy consumption, but also requires frequent shutdowns for cleaning in severe cases, hindering the continuous and stable operation of the evaporation system.

[0003] To alleviate the scaling and clogging problem of falling film evaporators, Chinese patent CN222173102U discloses a novel, high-efficiency, anti-clogging falling film evaporator. This design incorporates a pre-designed helical angle structure on the heat exchange tubes, causing repeated changes in the liquid film flow direction to create a helical shearing effect, reducing material viscosity and preventing scaling inside the tubes. While this solution improves flow conditions by altering the surface structure of the heat exchange tubes, the helical angle structure increases flow resistance within the tubes to some extent, potentially affecting the uniformity of liquid film distribution. Furthermore, the helical structure makes cleaning the scale layer more difficult after it forms. Chinese patent application CN120043394A discloses an automatically cleaning, anti-clogging falling film evaporator that utilizes liquid flow impact to drive a steel wire spiral to generate radial vibration and slow rotation, achieving automatic cleaning of the heat exchange tubes. Although this solution achieves online automatic cleaning, the long-term contact and friction between the steel wire spiral and the tube wall poses a risk of wear on the inner wall of the heat exchange tubes.

[0004] In summary, existing anti-clogging technologies for falling film evaporators mainly rely on surface structure improvement, mechanical scraping, or external cleaning devices. There is still a lack of a technical solution that can proactively prevent scaling on the inner wall of the heat exchange tubes by utilizing the evaporator's own operating status without increasing the risk of additional wear. Summary of the Invention

[0005] The core of this invention lies in using a linkage component to drive the micro-tube to rotate slightly laterally to generate shear force, thereby breaking the boundary layer and preventing dry wall scaling. It also improves steam flowability through the misalignment of the fan-shaped plate and precisely compensates for high scaling risk areas by the independent rotation of the outer tube. This solves the problems in the prior art where poor liquid film flowability, dry wall scaling and blockage, and lack of active online scaling prevention methods are all problems.

[0006] To solve the above problems, the present invention adopts the following technical solution.

[0007] A clog-resistant falling film evaporator for evaporation and concentration of black liquor from pulping includes a falling film evaporator, a separation tank, and two connecting pipes fixedly connected between the falling film evaporator and the separation tank. The upper end of the falling film evaporator is fixedly connected to a feed inlet, and the bottom of both the falling film evaporator and the separation tank are fixedly connected to a discharge port. The outer end of the falling film evaporator is fixedly connected from top to bottom to a steam inlet, an exhaust port, and a liquid outlet. The falling film evaporator is equipped with a falling film tube assembly, which includes two tube sheets and multiple uniformly distributed heat exchange tubes fixedly connected between the two tube sheets. The upper and lower ends of the heat exchange tubes are fixedly connected through the two tube sheets and are flush with the surface of the tube sheets. The heat exchange tube includes two fixed heat exchange sections connected to two tube sheets respectively, and a dynamic heat exchange section disposed between the two fixed heat exchange sections. The dynamic heat exchange section includes a micro-movement tube and two corrugated tubes fixedly connected to the upper and lower ends of the micro-movement tube respectively. The two corrugated tubes are fixedly connected to two adjacent fixed heat exchange sections respectively. Multiple micro-movement tubes are externally provided with a linkage assembly. The linkage assembly includes an annular bushing installed on the inner wall of the falling film evaporator, a linkage sleeve plate disposed on the micro-movement tube, and multiple drive units installed between the annular bushing and the linkage sleeve plate.

[0008] Furthermore, the upper end of the dynamic heat exchange section is not higher than the midpoint of the vertical direction of the heat exchange tube. Taking the bellows without twisting as the initial state, the rotation range of the linkage sleeve in the initial state does not exceed ±3°.

[0009] Furthermore, an annular slide rail is installed on the inner wall of the annular bushing, and multiple evenly distributed limiting strips are fixedly connected on the annular slide rail. A sliding interval is formed between two adjacent limiting strips, and multiple driving units correspond to multiple sliding intervals respectively.

[0010] Furthermore, the drive unit includes a connecting rod fixedly connected to the outer wall of the linkage plate and an electric slider connected to the annular slide rail. The electric slider is fixedly connected to the connecting rod, and the central angle corresponding to the sliding range is no greater than 6°.

[0011] Furthermore, the linkage plate includes multiple independent sector plates, which are staggered in the vertical direction. From a top view, the multiple sector plates form a complete circular plate and are symmetrical about the central axis of the falling film evaporator. Each sector plate corresponds to at least one drive unit, and the annular bushing is divided into arc segments corresponding to the number of sector plates. The multiple arc segments are at the same height as the multiple sector plates.

[0012] Furthermore, from a top-down perspective, the linkage sleeve is divided into a non-rotating zone at the center and a rotating zone on the outside. The non-rotating zone and the rotating zone are coaxially arranged, and multiple micro-movement tubes in the rotating zone are fixedly connected to an outer fixed ring, which is rotatably connected to the linkage sleeve.

[0013] Optionally, the outer fixed ring is connected to the linkage sleeve via an electric rotating ring.

[0014] Optionally, the outer fixed ring is connected to the linkage sleeve plate through a deflection assembly. The linkage sleeve plate has multiple pairs of self-rotating grooves that are coaxial with multiple outer fixed rings. Each pair of self-rotating grooves is symmetrical about the central axis of the corresponding outer fixed ring. The deflection assembly includes two push plates fixedly connected to the outer wall of the outer fixed ring. The push plates are slidably connected to the self-rotating grooves. The deflection assembly also includes two pairs of electromagnetic plates that correspond to two driving units. The two electromagnetic plates are fixedly embedded in the two vertical inner walls of the corresponding driving units.

[0015] Furthermore, when the electromagnetic plate is energized, it generates a magnetic attraction force on the push plate. Along the radial direction of the linkage sleeve plate, the central angles corresponding to the multiple self-rotating slots gradually increase, and the central angles of the self-rotating slots do not exceed 6°.

[0016] Compared with the prior art, the advantages of this invention are: (1) This solution uses a linkage component to drive the micro-movement tube to rotate slightly laterally, generating shear force near the wall to destroy the boundary layer, preventing the liquid film from drying and scaling due to increased viscosity, thus achieving active online prevention of scaling during evaporator operation. Compared with the spiral angle structure or steel wire spiral scraping scheme in the prior art, this implementation does not rely on the improvement of the flow channel structure, nor does it generate friction and wear with the tube wall. It utilizes the evaporator's own operating state to complete the scaling prevention, and the structure is simple and reliable.

[0017] (2) By setting the outer micro-movement tube as an independent rotation zone on the linkage sleeve plate, the outer heat exchange tube is driven by the outer fixed ring to rotate on the basis of the overall rotation (revolution), providing stronger local disturbance for the outer high-scaling risk area, accurately compensating for the insufficient anti-scaling effect on the outer side caused by uneven revolution amplitude. The synergistic effect of rotation and revolution realizes the uniformity of the anti-scaling effect of the whole tube bundle. Attached Figure Description

[0018] Figure 1 This is a perspective view of the present invention; Figure 2 This is a partial cross-sectional view of the present invention; Figure 3 This is a schematic diagram of the black liquor raw material concentration process of the present invention; Figure 4 This is a perspective view of the dynamic heat exchange section of the falling film tube assembly of the present invention. Figure 5 This is a perspective view of the linkage component portion of the present invention; Figure 6 This is a top view of the linkage component of the present invention; Figure 7 This is a top view of the linkage component of the present invention when it is a split structure. Figure 8 This is a schematic diagram illustrating the division of the self-rotating and non-rotating zones in the linkage component of the present invention. Figure 9 This is a top view of the deflection component portion of the linkage component of the present invention. Figure 10 This is a front view schematic diagram of the deflection component portion of the present invention; Figure 11 This is a schematic diagram of the deflection component of the present invention driving the heat exchange section to rotate slightly.

[0019] Explanation of the labels in the diagram: 1 Falling film evaporator, 11 Feed inlet, 12 Steam inlet, 13 Exhaust port, 14 Liquid outlet, 15 Feed outlet, 2 Separator, 3 Connecting pipe, 41 Tube sheet, 42 Heat exchange tube, 421 Micro-motion tube, 422 Corrugated pipe, 5 Linkage assembly, 51 Annular bushing, 52 Linkage sleeve plate, 53 Drive unit, 531 Connecting rod, 532 Electric slider, 501 Limiting strip, 502 Sliding section, 503 Self-rotating groove, 6 Outer fixed ring, 61 Electromagnetic plate, 62 Push plate. Detailed Implementation

[0020] The technical solutions will now be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention.

[0021] First implementation method: like Figures 1-2 A clog-resistant falling film evaporator for black liquor evaporation and concentration includes a falling film evaporator 1, a separation tank 2, and two connecting pipes 3 fixedly connected between the falling film evaporator 1 and the separation tank 2. The upper end of the falling film evaporator 1 is fixedly connected to a feed inlet 11, and the bottom of both the falling film evaporator 1 and the separation tank 2 are fixedly connected to discharge ports 15. From top to bottom, the outer end of the falling film evaporator 1 is fixedly connected to a steam inlet 12, an exhaust port 13, and a liquid discharge port 14. The falling film evaporator 1 contains a falling film tube assembly, which includes two tube sheets 41 and multiple evenly distributed heat exchange tubes 42 fixedly connected between the two tube sheets 41. The upper and lower ends of the heat exchange tubes 42 are respectively fixedly inserted through the two tube sheets 41 and flush with the surface of the tube sheets 41. Figure 3In operation, the raw material (black liquor) to be evaporated and concentrated is fed into the falling film evaporator 1 through the feed port 11. Then, under the action of the distributor, the raw material is evenly fed into multiple heat exchange tubes 42 and falls along their inner walls to form a uniform liquid film. At the same time, high-temperature water vapor enters the shell side of the falling film evaporator 1 through the steam inlet 12 and exchanges heat with the raw material liquid film in the multiple heat exchange tubes 42, causing the water in the raw material to evaporate and thus reducing the water content in the raw material, achieving concentration. The concentrated liquid then enters the bottom of the falling film evaporator 1 and is discharged from the feed port 15. Meanwhile, part of the steam evaporated from the raw material enters the separation tank 2 through the connecting pipe 3, where it undergoes secondary separation, causing the concentrated liquid to settle to the bottom. The separated steam is discharged from the top of the separation tank 2. In addition, during the above process, some of the unliquefied water vapor that enters the falling film evaporator 1 is discharged through the exhaust port 13, and some of the liquefied water is discharged from the drain port 14.

[0022] It is worth noting that a material distributor is provided between the top of the falling film tube assembly and the feed inlet 11. This is existing technology and not an improvement of this solution, so it is not described in detail.

[0023] like Figure 2 and Figure 4 The heat exchange tube 42 includes two fixed heat exchange sections connected to two tube sheets 41 respectively, and a dynamic heat exchange section disposed between the two fixed heat exchange sections. The dynamic heat exchange section includes a micro-movement tube 421 and two corrugated tubes 422 fixedly connected to the upper and lower ends of the micro-movement tube 421 respectively. The two corrugated tubes 422 are fixedly connected to two adjacent fixed heat exchange sections respectively. A linkage assembly 5 is disposed outside the multiple micro-movement tubes 421. The linkage assembly 5 includes an annular bushing 51 installed on the inner wall of the falling film evaporator 1, a linkage sleeve 52 disposed on the micro-movement tube 421, and multiple drive units 53 installed between the annular bushing 51 and the linkage sleeve 52. The drive unit 53 includes a linkage assembly 53. The connecting rod 531 fixedly connected to the outer wall of the sleeve plate 52 and the electric slider 532 connected to the annular slide rail are fixedly connected to the connecting rod 531. Through the setting of the linkage component 5, during the evaporation and concentration of the raw material, multiple micro-movement tubes 421 can be controlled to reciprocate in a small horizontal amplitude. The shear force generated in the horizontal direction causes the raw material on the inner wall of the heat exchange tube 42 to generate a small vortex, which can "flatten" the accumulated liquid film in the circumferential direction, increase the spreading area and wettability of the liquid film on the tube wall, so that the inner wall of the heat exchange tube 42 is not prone to dry wall phenomenon, reduce the scaling problem caused by dry wall, and achieve the anti-clogging effect.

[0024] The upper end of the dynamic heat exchange section is not higher than the midpoint of the heat exchange tube 42 in the vertical direction. Since the water content in the upper part is high and the water content of the liquid film in the lower part decreases due to evaporation, the overall fluidity becomes poor and the phenomenon of liquid film discontinuity is likely to occur. Therefore, this dynamic heat exchange section is concentrated in the part below the center line of the heat exchange tube 42, which helps to overcome the problems of liquid film discontinuity and dry wall caused by decreased fluidity.

[0025] Taking the bellows 422 in a non-twisted state as the initial state, the rotation range of the linkage sleeve 52 in the initial state does not exceed ±3°, that is, the overall rotation (revolution) amplitude is small. On the one hand, it effectively protects the connection point between the bellows 422 and the fixed heat exchange section, so that the connection is not easily subjected to excessive tensile force and is not easily damaged by the overall rotation (revolution). On the other hand, if the rotation angle is too large, the radial centrifugal force on the heat exchange tube 42 will be greater, which will change the motion pattern of the liquid film, causing it to deviate from the ideal free falling film state, and may even be thrown off the wall, causing flow chaos. If the rotation angle is too small, it is not possible to generate a sufficiently strong eddy near the wall to effectively destroy the boundary layer, resulting in the anti-structure effect of this scheme being insignificant.

[0026] like Figures 5-6 An annular slide rail is installed on the inner wall of the annular bushing 51. Multiple evenly distributed limiting strips 501 are fixedly connected to the annular slide rail. A sliding interval 502 is formed between two adjacent limiting strips 501. The central angle corresponding to the sliding interval 502 is no greater than 6°. Multiple driving units 53 correspond to multiple sliding intervals 502 respectively. The limiting strips 501 can effectively limit the rotation amplitude of the linkage sleeve 52 and effectively avoid the situation of excessive rotation amplitude.

[0027] It is worth noting that in order to ensure that the water vapor entering the falling film evaporator 1 from the steam inlet 12 can fully exchange heat with the liquid film in the multiple heat exchange tubes 42, a gap must be left between the linkage sleeve 52 and the annular bushing 51 to allow steam to pass through. If necessary, in addition to the holes that match the heat exchange tubes 42, additional through holes can be provided on the linkage sleeve 52 to improve the flow of steam on both sides above it.

[0028] Second implementation method: To improve the fluidity of steam, this embodiment makes the following improvements based on the first embodiment: like Figure 7 The linkage plate 52 includes multiple independent sector plates, which are staggered in the vertical direction. From a top view, the multiple sector plates form a complete circular plate and are symmetrical about the central axis of the falling film evaporator 1. Each sector plate corresponds to at least one drive unit 53, and the annular bushing 51 is divided into arc segments corresponding to the number of sector plates. The multiple arc segments are at the same height as the multiple sector plates.

[0029] The linkage plate 52 is divided into multiple parts. From a top view, it is still a complete circular plate, which can still synchronously control multiple micro-movement tubes 421 to perform small-amplitude reciprocating rotation in the circumference of the falling film evaporator 1. In the longitudinal direction, multiple fan-shaped plates are staggered, which makes the internal shell cavity of the falling film evaporator 1 well connected and less likely to affect the flow of steam, thereby reducing the impact on the evaporation and concentration process.

[0030] The third implementation method: Since the heat exchange efficiency between the multiple micro-movement tubes 421 located on the outer side and the steam is higher, the water content of the liquid film inside the corresponding micro-movement tube 421 is lower, and the probability of scaling is greater than that of the inner micro-movement tube 421 with lower heat exchange efficiency. Therefore, this embodiment further improves the linkage component 5 based on the first or second embodiment, as detailed below: like Figure 8 From a top-down perspective, the linkage sleeve 52 is divided into a non-rotating zone at the center and a rotating zone on the outside. The non-rotating zone and the rotating zone are coaxially arranged, and multiple micro-movement tubes 421 in the rotating zone are fixedly connected to an outer fixed ring 6. The outer fixed ring 6 is rotatably connected to the linkage sleeve 52. When multiple micro-movement tubes 421 rotate as a whole (revolve), the outer fixed ring 6 can also control the independent rotation of the micro-movement tubes 421 with higher heat exchange efficiency on the outside, that is, to provide stronger local disturbance for the high-scaling-risk area on the outside, accurately compensate for the uneven amplitude of the revolution, and achieve uniform anti-scaling effect of the entire tube bundle.

[0031] There are two possible rotation methods between the outer fixed ring 6 and the linkage sleeve 52. In specific implementation, one method can be selected according to the needs.

[0032] The outer fixed ring 6 is connected to the linkage sleeve 52 via an electric rotating ring. It is mainly electrically controlled and can precisely control the rotation angle, speed and frequency. Under the same volume, it can provide a larger driving torque than magnetic transmission and has a fast response speed.

[0033] like Figures 9-10 The outer fixed ring 6 is connected to the linkage sleeve plate 52 through the deflection assembly. The linkage sleeve plate 52 has multiple pairs of self-rotating grooves 503 that are coaxial with the multiple outer fixed rings 6 respectively. Each pair of self-rotating grooves 503 is symmetrical about the central axis of the corresponding outer fixed ring 6. The deflection assembly includes two push plates 62 fixedly connected to the outer wall of the outer fixed ring 6. The push plates 62 are slidably connected to the self-rotating grooves 503. The deflection assembly also includes two pairs of electromagnetic plates 61 that are respectively corresponding to the two drive units 53. The electromagnetic plates 61 can be made of high-temperature and corrosion-resistant materials such as iron-chromium soft magnetic alloy or high-temperature silicon steel sheets. In addition, in practice, the iron-chromium soft magnetic alloy or high-temperature silicon steel sheets are wrapped with fluororubber sealing rings and filled with epoxy resin potting to protect the internal iron-chromium soft magnetic alloy or high-temperature silicon steel sheets.

[0034] Two electromagnetic plates 61 are fixedly embedded in the two vertical inner walls of the corresponding drive unit 53. When the electromagnetic plates 61 are energized, they generate a magnetic attraction force on the push plate 62. Along the radial direction of the linkage sleeve 52, the central angles of the multiple self-rotating slots 503 gradually increase, and the central angles of the self-rotating slots 503 do not exceed 6°. In use, such as Figure 9 and Figure 11 Simultaneously, the control energizes the two corresponding electromagnetic plates 61 (de-energizes the other two corresponding electromagnetic plates 61) -- controls the on / off state of the two corresponding falling film evaporators 1 (energizes the other two corresponding electromagnetic plates 61), so that the push plate 62 is alternately subjected to clockwise and counterclockwise magnetic attraction forces, thereby driving the external fixed ring 6 to reciprocate and rotate.

[0035] Among them, the external fixed ring 6 magnetic control self-rotation drive method is a non-contact transmission, which has lower mechanical wear than electric control, resulting in low maintenance costs and frequency. In addition, it is not afraid of high humidity environment and is suitable for the high temperature and high humidity environment of 45-110℃ inside the evaporator.

[0036] Therefore, both methods have their advantages, and one can be chosen according to the specific needs during implementation.

[0037] The above description is merely a preferred embodiment of the present invention; it encompasses all the protection scope of the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solutions and improved concepts of the present invention, should be covered within the protection scope of the present invention.

Claims

1. Anti-blocking falling film evaporator device for evaporative concentration of pulp black liquor, comprising a falling film evaporator (1), a separation tank (2) and two communication pipes (3) fixedly connected between the falling film evaporator (1) and the separation tank (2), characterized in that: The upper end of the falling film evaporator (1) is fixedly connected to the feed inlet (11), and the bottom of the falling film evaporator (1) and the separation tank (2) are both fixedly connected to the discharge port (15). The outer end of the falling film evaporator (1) is fixedly connected to the steam inlet (12), the exhaust port (13) and the liquid discharge port (14) from top to bottom. The falling film evaporator (1) is provided with a falling film tube assembly. The falling film tube assembly includes two tube sheets (41) and multiple uniformly distributed heat exchange tubes (42) fixedly connected between the two tube sheets (41). The upper and lower ends of the heat exchange tubes (42) are fixedly connected through the two tube sheets (41) and are flush with the surface of the tube sheets (41). The heat exchange tube (42) includes two fixed heat exchange sections connected to two tube sheets (41) respectively and a dynamic heat exchange section disposed between the two fixed heat exchange sections. The dynamic heat exchange section includes a micro-movement tube (421) and two corrugated tubes (422) fixedly connected to the upper and lower ends of the micro-movement tube (421) respectively. The two corrugated tubes (422) are fixedly connected to two adjacent fixed heat exchange sections respectively. A linkage assembly (5) is provided on the outside of the multiple micro-movement tubes (421). The linkage assembly (5) includes an annular bushing (51) installed on the inner wall of the falling film evaporator (1), a linkage sleeve plate (52) disposed on the micro-movement tube (421), and multiple drive units (53) installed between the annular bushing (51) and the linkage sleeve plate (52).

2. The anti-clogging falling film evaporator for black liquor evaporation and concentration according to claim 1, characterized in that: The upper end of the dynamic heat exchange section is not higher than the midpoint of the vertical direction of the heat exchange tube (42). The initial state is that the bellows (422) is in a state without twisting. The rotation range of the linkage sleeve (52) in the initial state does not exceed ±3°.

3. The anti-clogging falling film evaporator for black liquor evaporation and concentration according to claim 2, characterized in that: The inner wall of the annular bushing (51) is equipped with an annular slide rail, and multiple evenly distributed limiting strips (501) are fixedly connected on the annular slide rail. A sliding interval (502) is formed between two adjacent limiting strips (501), and multiple driving units (53) correspond to multiple sliding intervals (502) respectively.

4. The anti-clogging falling film evaporator for evaporation and concentration of pulping black liquor according to claim 3, characterized in that: The drive unit (53) includes a connecting rod (531) fixedly connected to the outer wall of the linkage sleeve (52) and an electric slider (532) connected to the annular slide rail. The electric slider (532) is fixedly connected to the connecting rod (531), and the central angle corresponding to the sliding interval (502) is no greater than 6°.

5. The anti-clogging falling film evaporator for black liquor evaporation and concentration according to claim 4, characterized in that: The linkage sleeve (52) includes multiple independent sector plates, which are staggered in the vertical direction. From a top view, the multiple sector plates form a complete circular plate and are symmetrical about the central axis of the falling film evaporator (1). Each sector plate corresponds to at least one drive unit (53), and the annular bushing (51) is divided into arc segments corresponding to the number of sector plates. The multiple arc segments are at the same height as the multiple sector plates.

6. The anti-clogging falling film evaporator for evaporation and concentration of black liquor from pulping according to claim 4 or 5, characterized in that: From a top-down perspective, the linkage sleeve (52) is divided into a non-rotating area at the center and a rotating area on the outside. The non-rotating area and the rotating area are coaxially arranged, and multiple micro-movement tubes (421) in the rotating area are fixedly connected to an outer fixed ring (6). The outer fixed ring (6) is rotatably connected to the linkage sleeve (52).

7. The anti-clogging falling film evaporator for evaporation and concentration of pulping black liquor according to claim 6, characterized in that: The outer fixed ring (6) is connected to the linkage sleeve (52) via an electric rotating ring.

8. The anti-clogging falling film evaporator for black liquor evaporation and concentration according to claim 6, characterized in that: The outer fixed ring (6) is connected to the linkage sleeve plate (52) through the deflection assembly. The linkage sleeve plate (52) has multiple pairs of self-rotating grooves (503) that are coaxial with the multiple outer fixed rings (6). Each pair of self-rotating grooves (503) is symmetrical about the central axis of the corresponding outer fixed ring (6). The deflection assembly includes two push plates (62) that are fixedly connected to the outer wall of the outer fixed ring (6). The push plates (62) are slidably connected to the self-rotating grooves (503). The deflection assembly also includes two pairs of electromagnetic plates (61) that are respectively corresponding to the two driving units (53). The two electromagnetic plates (61) are fixedly embedded on the two vertical inner walls of the corresponding driving unit (53).

9. The anti-clogging falling film evaporator for black liquor evaporation and concentration according to claim 8, characterized in that: When the electromagnetic plate (61) is energized, it generates a magnetic attraction force on the push plate (62). Along the radial direction of the linkage sleeve plate (52), the central angles of the multiple self-rotating slots (503) gradually increase, and the central angles of the self-rotating slots (503) do not exceed 6°.

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