A rotary thin film evaporation device based on DMF raffinate recycling

Abstract

The application discloses a rotary thin film evaporation device based on DMF residual liquid recycling, and belongs to the technical field of DMF recycling, which comprises an evaporation component, and the evaporation component comprises an evaporation device main body, a rotating assembly for cloth is arranged in the evaporation device main body, a flow guide assembly for guiding DMF residual liquid is arranged in the evaporation device main body, and a steam baffle for blocking water vapor is arranged in the evaporation device main body. Through the uniform heating structure of the jacket type of the heating cylinder body matched with the heat conduction oil circulation, the DMF vaporization temperature interval can be accurately controlled and maintained stable, and the high-temperature decomposition of DMF is avoided. Through the synergistic effect of the rotary liquid distribution disc and the spiral scraper, the DMF residual liquid is forced to spread on the inner wall of the cylinder body to form a uniform ultra-thin liquid film, the material heating contact area is greatly increased, the heat exchange stroke is prolonged, the heat transfer and conduction efficiency is strengthened, the DMF vaporization rate is accelerated, and the overall residual liquid treatment and solvent recovery efficiency is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of DMF recycling technology, and more specifically, to a rotary thin-film evaporator based on DMF residual liquid recycling. Background Technology

[0002] N,N-Dimethylformamide (DMF), a highly potent polar organic solvent, is widely used in numerous industrial fields such as fine chemicals, polymer synthesis, pharmaceutical preparation, and textile printing and dyeing. Industrial production processes continuously generate large quantities of DMF residues. These residues contain a mixture of inorganic salts, polymers, organic colloidal byproducts, and easily gelling viscous impurities. Direct discharge without treatment not only causes severe environmental pollution but also leads to a significant waste of organic solvent resources and a substantial increase in hazardous waste disposal and operational costs for enterprises. Therefore, efficient separation, low-temperature evaporation, purification, and recovery of DMF industrial residues, along with solvent recycling, is an inevitable development requirement for energy conservation, emission reduction, and green production in the current industry.

[0003] Currently, the conventional methods for handling DMF residue are: using a single-layer direct-fall liquid distribution system or a simple fixed liquid distribution tray. The tray surface is a pure planar structure, relying solely on natural fall and simple centrifugal throwing to complete the liquid distribution. There is no multi-stage flow guidance or inclined flow stabilization structure, which leads to uncontrollable residual liquid throwing speed, excessively fast upper layer throwing, insufficient liquid supply to the lower layer, uneven liquid film thickness on the cylinder wall, difficulty in forming a uniform ultra-thin liquid film on the inner wall of the cylinder, small material heat contact area, low heat transfer efficiency, slow DMF vaporization rate, and low overall residual liquid treatment capacity and solvent recovery efficiency.

[0004] In view of this, we propose a rotary thin-film evaporator based on the recovery and utilization of DMF residual liquid. Summary of the Invention

[0005] Technical problem to be solved: The purpose of this invention is to provide a rotary thin-film evaporation device based on DMF residual liquid recycling, which solves the technical problems mentioned in the background art.

[0006] Technical solution: The present invention provides a rotary thin film evaporation device based on DMF residual liquid recycling, including an evaporation component, which includes an evaporation device body. The evaporation device body is provided with a rotating component for spreading the material inside, a flow guiding component for guiding the DMF residual liquid inside, and a vapor baffle plate for blocking water vapor inside. The evaporation device body includes a heating cylinder. The liquid distribution component includes a spreading assembly disposed inside the main body of the evaporator, which is used to evenly distribute the residual liquid on the inner wall of the heating cylinder. The spreading assembly is provided with a wear-resistant component for protecting the spiral scraper.

[0007] As an optional solution to the technical solution of this invention, the main body of the evaporation device includes an upper cylinder, an air outlet is provided on the side of the upper cylinder, a liquid inlet is provided on the side of the upper cylinder away from the air outlet, a heating cylinder is provided at the bottom of the upper cylinder, a heating tube is provided on the outer wall of the heating cylinder, a lower end cap is provided at the bottom of the heating cylinder, a discharge port is provided at the lower end of the lower end cap, a bearing seat is provided on the inner wall of the lower end cap, and the liquid inlet is located below the side of the air outlet.

[0008] As an optional solution to the technical solution of this invention, the rotating assembly includes a motor disposed above the upper cylinder, a speed reducer disposed at the bottom of the motor, a mechanical seal disposed at the bottom of the speed reducer, a rotating shaft rotatably connected to the bottom of the motor, a plurality of first liquid distribution plates and second liquid distribution plates fixedly connected to the rotating shaft, a plurality of leakage holes evenly disposed on the first liquid distribution plates and the second liquid distribution plates, and a bottom liquid distribution plate fixedly connected to the rotating shaft, and a slope disposed at the top of the first liquid distribution plate, the second liquid distribution plate and the bottom liquid distribution plate.

[0009] As an optional solution to the technical solution of this invention, the lower end of the rotating shaft extends through the speed reducer, mechanical seal, and upper cylinder to the interior of the heating cylinder. The lower end of the rotating shaft is rotatably connected to the bearing seat. A plurality of first liquid distribution plates and a plurality of second liquid distribution plates are staggered. The leakage holes on the first liquid distribution plates and the leakage holes on the second liquid distribution plates are staggered. The bottom liquid distribution plate is located below the second liquid distribution plates and the first liquid distribution plates. The first liquid distribution plates, the second liquid distribution plates, and the bottom liquid distribution plate are all located inside the heating cylinder. The steam baffle is fixedly connected to the rotating shaft. The steam baffle is umbrella-shaped and located inside the upper cylinder. The steam baffle is located between the air outlet and the liquid inlet.

[0010] By adopting the above technical solution, a multi-layer liquid distribution plate is set up so that the residual liquid can be uniformly diffused radially.

[0011] As an optional solution of the technical solution in this invention document, the flow guiding component includes a distributor disposed at the bottom of the inner wall of the upper cylinder, the top of the distributor is provided with a liquid inlet groove, the distributor is provided with three exhaust grooves, the top of the exhaust grooves is provided with a chamfer, and the bottom of the distributor is provided with a rotating groove.

[0012] As an optional solution to the technical solution of this invention, the top of the distributor is provided with an inverted conical surface, the exhaust groove penetrates the distributor, the distributor is located below the baffle plate, and the liquid inlet groove is connected to the liquid inlet.

[0013] By adopting the above technical solution, a flow guiding component is set up to guide the residual liquid entering the device.

[0014] As an optional solution of the technical solution in this invention document, the material spreading assembly includes a turntable fixedly connected to a rotating shaft, a connecting groove on the turntable, a plurality of leakage grooves at the center of the turntable, two spiral scrapers fixedly connected to the bottom of the turntable, an embedding groove on the bottom surface of the spiral scrapers, and a scraping ring fixedly connected to the bottom of the spiral scrapers.

[0015] As an optional solution to the technical solution of this invention, the spiral scraper is made of stainless steel, the spiral scraper adopts an inclined scraper blade structure, and the spiral angle gradually increases continuously. The scraper ring is located below the slope, and the scraper ring is rotatably connected to the inner wall of the heating cylinder. The scraper ring is fixedly connected to the rotating shaft through a connecting plate, wherein the cross-section of the connecting plate is an isosceles triangle. The bottom of the scraper ring and the bottom of the connecting plate are both in contact with the top of the bearing seat. The leakage groove is rotatably connected to the inner wall of the rotating groove. The size of the connecting groove is larger than the size of the exhaust groove. The size of the turntable is larger than the size of the liquid distribution plate. The first liquid distribution plate, the second liquid distribution plate, and the bottom liquid distribution plate are all located between two spiral scrapers. The side of the spiral scraper near the liquid distribution plate is in contact with the side wall of the liquid distribution plate. The shape of the inlay groove is a through-type dovetail shape.

[0016] By adopting the above technical solution, the material spreading component can be set up to make the residual liquid form a uniform film on the pipe wall.

[0017] As an optional solution to the technical solution of this invention, the wear-resistant component includes a ceramic strip disposed at the bottom of the spiral scraper, and an inlay block is disposed on the ceramic strip.

[0018] As an optional solution of the technical solution in this invention document, the size of the inlay block is adapted to the size of the inlay groove, the inlay block and the inlay groove are snapped together, the ceramic strip is made of zirconium oxide material and its surface is polished, the shape of the ceramic strip is adapted to the shape of the spiral scraper, the cross-section of the ceramic strip is "L" shaped, the surface of the ceramic strip is attached to the spiral scraper, and the side of the ceramic strip away from the spiral scraper is attached to the inner wall of the heating cylinder.

[0019] By adopting the above technical solution, wear-resistant components can be installed to protect the spiral scraper.

[0020] Beneficial effects: One or more technical solutions provided in this invention have at least the following technical effects or advantages: 1. By combining heat transfer oil circulation with the jacketed uniform heating structure of the heating cylinder, the temperature can be precisely controlled and a stable DMF vaporization temperature range can be maintained, avoiding high-temperature decomposition of DMF; and through the synergistic action of the rotating liquid distribution plate and the spiral scraper, the residual DMF liquid is forcibly spread on the inner wall of the cylinder to form a uniform ultra-thin liquid film, which greatly increases the heat contact area of ​​the material, extends the heat exchange path, enhances the heat transfer efficiency, accelerates the vaporization rate of DMF, and effectively improves the overall residual liquid treatment and solvent recovery efficiency.

[0021] 2. The multi-stage liquid distribution tray combined with the sloping structure design utilizes centrifugal force to achieve uniform radial diffusion of residual liquid. The sloping structure can effectively obstruct and stabilize the flow, control the rate at which the upper layer of residual liquid is thrown out, and allow excess residual liquid to be smoothly guided downwards through the leakage holes, balancing the liquid distribution between the upper and lower layers and solving the problem of uneven liquid film distribution on the pipe wall. The sloping surface has no low-lying dead corners where material accumulates, which can effectively prevent local retention and concentration of DMF residual liquid and the resulting gel adhesion, reduce the risk of flow channel blockage, and ensure the stability of continuous liquid distribution.

[0022] 3. The spiral scraper features a continuously gradually expanding small angle of inclination and a seamless structure, avoiding dead zones and stagnant areas found in traditional spiral joints. The small angle of inclination in the upper spiral slows down the downward flow of residual liquid, extending the heat exchange time of the material and ensuring full vaporization of DMF. The larger angle of inclination in the lower spiral allows for rapid downward movement of concentrated impurities, balancing the needs of efficient evaporation and smooth slag discharge. Simultaneously, the small-angle spiral assists in guiding and spreading the material, preventing the liquid film from descending too quickly and causing incomplete vaporization of DMF before discharge, significantly improving the DMF recovery rate.

[0023] 4. Furthermore, the spiral scraper adopts a forward-inclined and outward-inclined composite inclined blade structure, relying on the centrifugal force to guide the residual liquid to move only towards the heating cylinder wall, avoiding material accumulation and retention on the scraper surface; at the same time, the scraper base is made of stainless steel, with mirror-polished zirconia ceramic strips inlaid on the outer edge, which has low surface energy, high wear resistance, and strong anti-stick properties, which can effectively resist the adhesion of salt, polymer colloids, and gel impurities in DMF residual liquid, reduce component wear, adapt to long-term continuous operation under harsh working conditions with high impurities, and reduce equipment scaling and the frequency of downtime for cleaning.

[0024] 5. Secondly, the scraper ring adopts an isosceles triangular connecting plate that fits snugly with the bearing seat. During equipment operation, it can generate continuous radial shear force, which, combined with the rotational centrifugal force, forms an autonomous anti-adhesion structure. This effectively inhibits the accumulation and scaling of impurities and viscous materials at the joint between the scraper ring and the bearing seat. The key rotating parts have strong self-cleaning ability, further improving the overall operational reliability and service life of the equipment.

[0025] 6. The spiral scraper continuously and dynamically scrapes and renews the material on the cylinder wall, forcing the formation of a uniform and ultra-thin evaporative liquid film, which greatly increases the heat exchange contact area, enhances heat transfer efficiency, and accelerates the vaporization rate of DMF. High-boiling-point salts, polymers, and colloidal heavy components in the residual liquid cannot be vaporized and can be concentrated and pushed to the bottom by the scraper for periodic discharge, achieving efficient separation of solvent and heavy impurities. The entire set of equipment integrates continuous feeding, uniform liquid distribution, thin film evaporation, impurity separation, and steam purification, with strong automated continuous operation capability and high DMF residual liquid treatment efficiency. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of a rotary thin-film evaporator based on DMF residual liquid recovery.

[0028] Figure 2 This is a schematic cross-sectional view of the rotating component in a rotary thin-film evaporator based on DMF residual liquid recovery.

[0029] Figure 3 A rotary thin-film evaporator based on DMF residual liquid recovery Figure 2 Enlarged structural diagram at point A in the middle.

[0030] Figure 4 This is a schematic cross-sectional view of the flow guiding component in a rotary thin-film evaporator based on DMF residual liquid recovery.

[0031] Figure 5 This is a three-dimensional structural diagram of the material spreading component in a rotary thin-film evaporator based on DMF residual liquid recycling.

[0032] Figure 6 This is a schematic diagram showing the structural relationship and fit between the scraper ring and the ceramic strip in a rotary thin-film evaporator based on DMF residual liquid recovery.

[0033] Figure 7 This is a schematic cross-sectional view of the flow guide component of a rotary thin-film evaporator based on DMF residual liquid recycling.

[0034] Figure 8 This is a schematic diagram showing the structural relationship and fit between the scraper ring and the bearing housing in a rotary thin-film evaporator based on DMF residual liquid recovery.

[0035] Figure 9This is a bottom view of the spiral scraper structure in a rotary thin-film evaporator based on DMF residual liquid recovery.

[0036] Figure 10 This is a schematic diagram of the three-dimensional structure of the ceramic strip in a rotary thin-film evaporator based on DMF residual liquid recovery.

[0037] Explanation of the numbers in the diagram: 10. Main body of the evaporator; 101. Upper cylinder; 102. Gas outlet; 103. Heating cylinder; 104. Heating tube; 105. Lower end cap; 106. Discharge port; 107. Bearing seat; 108. Liquid inlet; 11. Rotating assembly; 111. Motor; 112. Reducer; 113. Mechanical seal; 114. Rotating shaft; 115. First liquid distribution plate; 116. Second liquid distribution plate; 117. Leakage hole; 118. Bottom liquid distribution plate; 119. Slope; 12. Flow guiding assembly; 121. Distributor; 122. Liquid inlet tank; 123. Exhaust tank; 124. Chamfer; 125. Rotating tank; 13. Steam baffle; 20. Material spreading assembly; 201. Turntable; 202. Connecting groove; 203. Leakage groove; 204. Spiral scraper; 205. Embedding groove; 206. Scraper ring; 21. Wear-resistant component; 211. Ceramic strip; 212. Embedding block. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or a link; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] Reference Figures 1 to 10 This invention provides a rotary thin-film evaporator based on DMF residual liquid recycling, including an evaporation component, which includes an evaporator body 10. The evaporator body 10 has a rotating component 11 for fabric application inside, a flow guiding component 12 for guiding DMF residual liquid inside, and a vapor baffle 13 for blocking water vapor inside. The evaporator body 10 includes a heating cylinder 103. The liquid distribution component includes a spreading assembly 20 disposed inside the main body 10 of the evaporator, which is used to evenly distribute the residual liquid on the inner wall of the heating cylinder 103. The spreading assembly 20 is provided with a wear-resistant component 21 for protecting the spiral scraper 204.

[0042] Reference Figure 1 and Figure 2 This invention provides a rotary thin-film evaporator based on DMF residual liquid recycling. The main body 10 of the evaporator includes an upper cylinder 101, an air outlet 102 on the side of the upper cylinder 101, a liquid inlet 108 on the side of the upper cylinder 101 away from the air outlet 102, a heating cylinder 103 at the bottom of the upper cylinder 101, a heating tube 104 on the outer wall of the heating cylinder 103, a lower end cap 105 at the bottom of the heating cylinder 103, a discharge port 106 at the lower end of the lower end cap 105, a bearing seat 107 on the inner wall of the lower end cap 105, and the liquid inlet 108 located below the air outlet 102.

[0043] Reference Figures 2 to 8This invention provides a rotary thin-film evaporator based on DMF residual liquid recycling. The rotating assembly 11 includes a motor 111 disposed above the upper cylinder 101. A speed reducer 112 is disposed at the bottom of the motor 111, and a mechanical seal 113 is disposed at the bottom of the speed reducer 112. A rotating shaft 114 is rotatably connected to the bottom of the motor 111. A plurality of first liquid distribution plates 115 and second liquid distribution plates 116 are fixedly connected to the rotating shaft 114. A plurality of leakage holes 117 are evenly disposed on the first liquid distribution plates 115 and second liquid distribution plates 116. A bottom liquid distribution plate 118 is fixedly connected to the rotating shaft 114. A ramp 119 is disposed at the top of the first liquid distribution plate 115, the second liquid distribution plate 116 and the bottom liquid distribution plate 118. The lower end of the rotating shaft 114 extends through the reducer 112, the mechanical seal 113, and the upper cylinder 101 into the interior of the heating cylinder 103. The lower end of the rotating shaft 114 is rotatably connected to the bearing seat 107. Several first liquid distribution plates 115 and several second liquid distribution plates 116 are staggered. The leakage holes 117 on the first liquid distribution plates 115 and the leakage holes 117 on the second liquid distribution plates 116 are staggered. The bottom liquid distribution plate 118 is located below the second liquid distribution plates 116 and the first liquid distribution plates 115. The first liquid distribution plates 115, the second liquid distribution plates 116, and the bottom liquid distribution plate 118 are all located inside the heating cylinder 103. The steam baffle plate 13 is fixedly connected to the rotating shaft 114. The steam baffle plate 13 is umbrella-shaped and located inside the upper cylinder 101. The steam baffle plate 13 is located between the air outlet 102 and the liquid inlet 108. By combining the heat transfer oil circulation with the jacketed uniform heating structure of the heating cylinder 103, the temperature can be precisely controlled and a stable DMF vaporization temperature range can be maintained, avoiding high-temperature decomposition of DMF. Furthermore, through the synergistic action of the rotating liquid distribution plate and the spiral scraper 204, the DMF residual liquid is forcibly spread thinly on the inner wall of the cylinder to form a uniform ultra-thin liquid film, which greatly increases the material heat contact area, extends the heat exchange path, enhances heat transfer efficiency, accelerates the DMF vaporization rate, and effectively improves the overall residual liquid treatment and solvent recovery efficiency. The design employs a multi-stage liquid distribution tray combined with a slope 119 structure. Centrifugal force is used to achieve uniform radial diffusion of residual liquid. The slope 119 can effectively impede and stabilize the flow, controlling the rate at which the upper layer of residual liquid is thrown out. Excess residual liquid is then smoothly guided downwards through the leakage holes 117, balancing the liquid distribution between the upper and lower layers and solving the problem of uneven liquid film distribution on the pipe wall. The slope has no low-lying dead corners where material accumulates, which can effectively prevent local retention and concentration of DMF residual liquid, thus avoiding gel adhesion, reducing the risk of flow channel blockage, and ensuring the stability of continuous liquid distribution.

[0044] Reference Figure 3 , Figure 4 and Figure 7This invention provides a rotary thin-film evaporator based on DMF residual liquid recycling. The flow guiding component 12 includes a distributor 121 disposed at the bottom of the inner wall of the upper cylinder 101. The top of the distributor 121 is provided with a liquid inlet groove 122. The distributor 121 is provided with three exhaust grooves 123. The top of the exhaust grooves 123 is provided with a chamfer 124. The bottom of the distributor 121 is provided with a rotating groove 125. The top of the distributor 121 is provided with an inverted conical surface, the exhaust groove 123 passes through the distributor 121, the distributor 121 is located below the baffle plate 13, and the liquid inlet groove 122 is connected to the liquid inlet 108.

[0045] Reference Figures 2 to 9 This invention provides a rotary thin-film evaporation device based on DMF residual liquid recycling. The material spreading assembly 20 includes a rotating shaft 114 on which a turntable 201 is fixedly connected. A connecting groove 202 is opened on the turntable 201. Several leakage grooves 203 are opened at the center of the turntable 201. Two spiral scrapers 204 are fixedly connected to the bottom of the turntable 201. An embedding groove 205 is opened on the bottom surface of the spiral scraper 204. A scraping ring 206 is fixedly connected to the bottom of the spiral scraper 204. The spiral scraper 204 is made of stainless steel and adopts an inclined scraper blade structure with a continuously increasing spiral angle. The scraper ring 206 is located below the slope 119 and is rotatably connected to the inner wall of the heating cylinder 103. The scraper ring 206 is fixedly connected to the rotating shaft 114 through a connecting plate. The cross-section of the connecting plate is an isosceles triangle. The bottom of the scraper ring 206 and the bottom of the connecting plate are both in contact with the top of the bearing seat 107. The leakage groove 203 is rotatably connected to the inner wall of the rotating groove 125. The size of the connecting groove 202 is larger than the size of the exhaust groove 123. The size of the turntable 201 is larger than the size of the liquid distribution plate. The first liquid distribution plate 115, the second liquid distribution plate 116, and the bottom liquid distribution plate 118 are all located between the two spiral scrapers 204. The side of the spiral scraper 204 closest to the liquid distribution plate is in contact with the side wall of the liquid distribution plate. The shape of the inlay groove 205 is a through-type dovetail shape. The spiral scraper 204 features a continuously gradually expanding small-angle spiral with no segmented splicing, avoiding dead corners and stagnant zones found in traditional spiral joints. The small angle of the upper spiral slows down the downward flow of residual liquid, extending the heat exchange time of the material and ensuring full vaporization of DMF. The larger angle of the lower spiral can quickly push concentrated impurities downward, balancing the needs of efficient evaporation and smooth slag discharge. At the same time, the small-angle spiral assists in guiding and spreading the material, preventing the liquid film from descending too quickly and causing DMF to be discharged before complete vaporization, significantly improving the DMF recovery rate.

[0046] Reference Figures 3 to 10This invention provides a rotary thin-film evaporator based on DMF residual liquid recycling. The wear-resistant component 21 includes a ceramic strip 211 disposed at the bottom of the spiral scraper 204. An insert block 212 is disposed on the ceramic strip 211. The size of the insert block 212 is adapted to the size of the insert groove 205. The insert block 212 and the insert groove 205 are engaged. The ceramic strip 211 is made of zirconium oxide and its surface is polished. The shape of the ceramic strip 211 is adapted to the shape of the spiral scraper 204. The cross-section of the ceramic strip 211 is "L" shaped. The ceramic strip 211 is in contact with the surface of the spiral scraper 204. The side of the ceramic strip 211 away from the spiral scraper 204 is in contact with the inner wall of the heating cylinder 103. Furthermore, the spiral scraper 204 adopts a forward-inclined and outward-inclined composite inclined blade structure. Relying on the centrifugal force guidance, it ensures that the residual liquid only moves towards the heating cylinder wall, preventing material from accumulating and stagnating on the scraper surface. At the same time, the scraper base is made of stainless steel, with mirror-polished zirconia ceramic strips 211 inlaid on the outer edge. These strips have low surface energy, high wear resistance, and strong anti-stick properties, which can effectively resist the adhesion of salt, polymer colloids, and gel impurities in the DMF residual liquid, reduce component wear, and adapt to long-term continuous operation under harsh working conditions with high impurities, thereby reducing equipment scaling and the frequency of downtime for cleaning.

[0047] This invention provides a rotary thin-film evaporator based on DMF residual liquid recovery and utilization, the working principle and usage process of which are as follows: First, the interior of the main body 10 of the evaporation device is evacuated to maintain a negative pressure vacuum environment, which can significantly reduce the vaporization temperature of DMF, achieve low-temperature evaporation, and avoid the problems of high-temperature oxidation and decomposition failure of DMF. Then, heat transfer oil is introduced into the heating tube 104 to uniformly heat the heating cylinder 103, so that its temperature is within the temperature range of DMF vaporization. At the same time, the motor 111 is started to make the rotating shaft 114 rotate under the deceleration of the reduction gear 112, thereby driving the liquid distribution plate and spiral scraper 204 inside the heating cylinder 103 to rotate. The residual DMF solution is then injected into the upper cylinder 101 through the inlet 108. Guided by the inlet 122, it flows downward along the inverted conical surface at the top of the distributor 121 and finally falls into the first distribution plate 115 inside the heating cylinder 103 through the drain 203. After the residual solution falls onto the first distribution plate 115, some of it will move outward under the action of centrifugal force and eventually overcome the ramp 119 to be thrown onto the inner wall of the heating cylinder 103. Some of the liquid will fall into the lower second distribution plate 116 through the drain hole 117, so that the excess residual solution is smoothly guided and transferred to the lower distribution plate step by step. The ramp 119 on the distribution plate can play a certain role in obstructing the flow and prevent a large amount of residual solution from being quickly thrown to the pipe wall in the upper layer, resulting in a large difference in liquid volume between the upper and lower layers and uneven film formation on the pipe wall. After the residual liquid is thrown against the pipe wall, it will be continuously scraped, pushed and guided downward by the rotating spiral scraper 204, which will force the liquid to be spread into a uniform ultra-thin liquid film on the inner wall of the heating cylinder 103. This will greatly increase the heating area of ​​the liquid film, extend the effective heat exchange path, enhance heat transfer, and make the DMF component in it vaporize rapidly. At the same time, the scraper continuously and dynamically updates the liquid film to prevent the cylinder wall from dry and coking, and the material from overheating and deteriorating. In addition, the high boiling point salts, polymers and colloidal heavy impurities in the residual liquid cannot be vaporized and will be gradually pushed downward by the spiral scraper 204 to collect inside the lower end cap 105. After concentration, it will be discharged from the discharge port 106. The spiral scraper 204 uses a small spiral angle, and it takes many rotations to move the liquid downward a small distance. The liquid film itself is very thin, and it will flow downward slowly under the action of gravity. The spiral is only an auxiliary and uniform downward force to make it spread more evenly. It is not a forced push, so as to avoid the situation where the liquid film falls too quickly due to the excessive angle, causing some DMF components to be pushed to the lower end cap 105 before they have vaporized. Secondly, the spiral scraper 204 adopts a continuous, gradually expanding small-angle spiral. The spiral angle decreases as it goes up and the downward movement slows down, allowing the residual liquid to be fully heated. The spiral angle increases as it goes down, which is conducive to slag discharge. This ensures the evaporation effect of DMF in the upper part and prevents material accumulation at the bottom. It also eliminates the dead corners of traditional segmented structures, solving the problems of material accumulation, coking, and flow stagnation at the joints of segmented spirals. This makes the liquid film descend smoothly without stagnant areas and avoids scaling and material jamming at the joints. To address the viscosity of DMF residue, the spiral scraper 204 uses stainless steel as its base and is inlaid with zirconia ceramic strips 211 on its outer edge. The working surface is mirror-polished to improve its anti-sticking and wear-resistant properties, making it suitable for long-term scraping of high-salt, high-impurity DMF. It reduces surface energy, making it difficult for DMF residue to adhere to the scraper. Furthermore, the spiral scraper 204 adopts an inclined scraper blade structure, which is not perpendicular to the plane of rotation but tilted outward and forward at a certain angle. This ensures that once the liquid comes into contact with the spiral scraper 204, it can only move towards the outer cylinder wall under the action of centrifugal force, preventing it from accumulating on its surface. This combination can further prevent material retention, coking, or rotation with the scraper. Meanwhile, the connecting plate of the scraper ring 206 is an isosceles triangle and fits against the top of the bearing seat 107. When the scraper ring 206 rotates, it cooperates with the bearing seat 107 to generate radial shear force. This, combined with the centrifugal force generated when the scraper ring 206 rotates, can prevent impurities from adhering to the scraper ring 206 and the bearing seat 107. The vaporized DMF mixture rises and passes through the connecting channel 202 and the exhaust channel 123 before reaching the baffle plate 13. Due to its large area and inverted blocking layout, it can physically block the liquid material, allowing only the gaseous DMF vapor to pass through. This traps most of the liquid entrainment, preventing liquid from being carried by the vapor and reducing the vapor velocity. As the velocity decreases, the colloidal particles, salt dust, and viscous gel fragments mixed in the vapor lose their upward momentum and fall back to the lower liquid distribution area and evaporation area by gravity, reducing gaseous impurities. At the same time, it can also play a role in rectifying and guiding the airflow, making the DMF vapor rise evenly and gently along the outer edge of the baffle plate. This stabilizes the airflow and prevents the vapor from concentrating and rushing directly to the top exhaust port 102, which could cause local eddies or turbulence. After the DMF vapor is discharged from the heating cylinder 103, further gas-liquid defoaming purification and staged condensation and liquefaction can complete the recycling of DMF.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rotary thin-film evaporator based on DMF residual liquid recovery and utilization, characterized in that: include An evaporation component includes an evaporation device body (10), the evaporation device body (10) having a rotating assembly (11) for fabric feeding inside, a flow guiding assembly (12) for guiding DMF residue inside, and a baffle plate (13) for blocking water vapor inside, wherein the evaporation device body (10) includes a heating cylinder (103). The liquid distribution component includes a spreading assembly (20) disposed inside the main body (10) of the evaporator, for distributing the residual liquid evenly on the inner wall of the heating cylinder (103), and the spreading assembly (20) is provided with a wear-resistant component (21) for protecting the spiral scraper (204). The rotating assembly (11) includes a rotating shaft (114) disposed inside the main body (10) of the evaporator. Several first liquid distribution plates (115) and second liquid distribution plates (116) for multi-stage liquid distribution are fixedly connected to the rotating shaft (114). Several leakage holes (117) are evenly arranged on the first liquid distribution plates (115) and the second liquid distribution plates (116). A bottom liquid distribution plate (118) is fixedly connected to the rotating shaft (114). The top of the first liquid distribution plate (115), the second liquid distribution plate (116) and the bottom liquid distribution plate (118) are all provided with slopes (119).

2. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 1, characterized in that: The main body (10) of the evaporation device includes an upper cylinder (101), an air outlet (102) is provided on the side of the upper cylinder (101), a liquid inlet (108) is provided on the side of the upper cylinder (101) away from the air outlet (102), a heating cylinder (103) is provided at the bottom of the upper cylinder (101), a heating tube (104) is provided on the outer wall of the heating cylinder (103), a lower end cap (105) is provided at the bottom of the heating cylinder (103), a discharge port (106) is provided at the lower end of the lower end cap (105), a bearing seat (107) is provided on the inner wall of the lower end cap (105), and the liquid inlet (108) is located below the air outlet (102).

3. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 2, characterized in that: The rotating assembly (11) also includes a motor (111) disposed above the upper cylinder (101), a speed reducer (112) disposed at the bottom of the motor (111), a mechanical seal (113) disposed at the bottom of the speed reducer (112), and a rotating shaft (114) rotatably connected to the bottom of the motor (111).

4. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 3, characterized in that: The lower end of the rotating shaft (114) extends through the reducer (112), mechanical seal (113), and upper cylinder (101) into the interior of the heating cylinder (103). The lower end of the rotating shaft (114) is rotatably connected to the bearing seat (107). Several first liquid distribution plates (115) and several second liquid distribution plates (116) are staggered. The leakage holes (117) on the first liquid distribution plates (115) and the leakage holes (117) on the second liquid distribution plates (116) are staggered. The bottom distribution... The liquid tray (118) is located below the second liquid distribution tray (116) and the first liquid distribution tray (115). The first liquid distribution tray (115), the second liquid distribution tray (116) and the bottom liquid distribution tray (118) are all located inside the heating cylinder (103). The steam baffle (13) is fixedly connected to the rotating shaft (114). The steam baffle (13) is umbrella-shaped. The steam baffle (13) is located inside the upper cylinder (101). The steam baffle (13) is located between the gas outlet (102) and the liquid inlet (108).

5. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 3, characterized in that: The flow guiding assembly (12) includes a distributor (121) disposed at the bottom of the inner wall of the upper cylinder (101). The top of the distributor (121) is provided with a liquid inlet groove (122), and the distributor (121) is provided with three exhaust grooves (123). The top of the exhaust grooves (123) is provided with a chamfer (124), and the bottom of the distributor (121) is provided with a rotating groove (125).

6. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 5, characterized in that: The top of the distributor (121) is provided with an inverted conical surface, the exhaust groove (123) passes through the distributor (121), the distributor (121) is located below the baffle plate (13), and the liquid inlet groove (122) is connected to the liquid inlet (108).

7. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 5, characterized in that: The material spreading assembly (20) includes a rotating shaft (114) on which a turntable (201) is fixedly connected. A connecting groove (202) is provided on the turntable (201). Several leakage grooves (203) are provided at the center of the turntable (201). Two spiral scrapers (204) are fixedly connected to the bottom of the turntable (201). An inlay groove (205) is provided on the bottom surface of the spiral scraper (204). A scraper ring (206) is fixedly connected to the bottom of the spiral scraper (204).

8. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 7, characterized in that: The spiral scraper (204) is made of stainless steel. The spiral scraper (204) adopts an inclined scraper blade structure, and the spiral angle gradually increases. The scraper ring (206) is located below the slope (119). The scraper ring (206) is rotatably connected to the inner wall of the heating cylinder (103). The scraper ring (206) is fixedly connected to the rotating shaft (114) through a connecting plate. The cross-section of the connecting plate is an isosceles triangle. The bottom of the scraper ring (206) and the bottom of the connecting plate are both in contact with the top of the bearing seat (107). The inner wall of the leakage groove (203) and the rotating groove (125) are rotatably connected. The size of the connecting groove (202) is larger than the size of the exhaust groove (123). The size of the turntable (201) is larger than the size of the liquid distribution plate. The first liquid distribution plate (115), the second liquid distribution plate (116) and the bottom liquid distribution plate (118) are all located between two spiral scrapers (204). The spiral scraper (204) is close to the side wall of the liquid distribution plate and fits against it. The shape of the inlay groove (205) is a through-type dovetail shape.

9. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 7, characterized in that: The wear-resistant component (21) includes a ceramic strip (211) disposed at the bottom of the spiral scraper (204), and an inlay block (212) is disposed on the ceramic strip (211).

10. The rotary thin-film evaporator based on DMF residual liquid recovery and utilization according to claim 9, characterized in that: The size of the inlay block (212) is adapted to the size of the inlay groove (205), and the inlay block (212) and the inlay groove (205) are snapped together. The ceramic strip (211) is made of zirconium oxide and its surface is polished. The shape of the ceramic strip (211) is adapted to the shape of the spiral scraper (204). The cross-section of the ceramic strip (211) is "L" shaped. The surface of the ceramic strip (211) is attached to the surface of the spiral scraper (204). The side of the ceramic strip (211) away from the spiral scraper (204) is attached to the inner wall of the heating cylinder (103).

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