Self-circulating thin film distillation apparatus and method

Abstract

This application relates to a self-circulating thin-film distillation apparatus and method. The apparatus includes a main body, an inner tube, a heating medium sleeve assembly, and a bowl-shaped end cap. The inner tube is disposed within the cylinder to form a material reflux annular gap, and its interior contains a heating tube bundle with staggered support baffles. The bowl-shaped end cap is centrally closed, with its concave surface facing the opening at the top of the inner tube. Driven by the lift force of the stripping gas, the material to be distilled climbs along the outer wall of the heating tube bundle, is heated, and is guided by the baffles to rise in an S-shaped path. After the mixed fluid impacts the bowl-shaped end cap, the gas phase enters the separation chamber through the edge flow gap and is discharged, while the liquid phase falls into the reflux annular gap through the flow gap and descends to the bottom by gravity, achieving self-circulation without power. This invention eliminates mechanical rotating parts and an external circulation pump, solves the problems of dynamic sealing and high-viscosity material circulation under high temperature and high vacuum conditions, and improves heat transfer efficiency and effectively prevents coking on the heating surface by utilizing a geometric cooperative structure.

Description

Technical Field

[0001] This application relates to the field of distillation processing technology, and in particular to a self-circulating thin-film distillation apparatus and method. Background Technology

[0002] In the production and processing of chemical products such as fatty acids and their derivatives, distillation often produces residues at the end of the process that are characterized by high viscosity, high boiling point, low liquid content, and high heat sensitivity. In order to further recover valuable light components from these residues, deep high-temperature high-vacuum distillation separation is usually required in industry.

[0003] Currently, the main equipment for processing such high-viscosity materials is the scraped film evaporator and the conventional falling film evaporator. However, existing technologies have the following drawbacks in practical applications: First, scraped film evaporators rely on internal rotating mechanical scrapers to force the material to form a film. Under high temperature and high vacuum conditions, the dynamic sealing technology of the rotating parts is extremely difficult and prone to leakage, which can easily disrupt the vacuum. Air leakage into the evaporator can easily ignite the material to be distilled at high temperatures, leading to accidents. At the same time, the continuous friction between the mechanical scraper and the tube wall can cause severe wear, resulting in a complex equipment structure and high operating and maintenance costs.

[0004] Secondly, although conventional falling film evaporators eliminate rotating parts, they rely on the gravity of the material to form a film from top to bottom, which requires a relatively high feed rate. When processing residues with very low liquid content and high viscosity, the fluid flow is poor, making it easy for flow deviation or interruption to occur, making it difficult to form a continuous liquid film on the heated wall surface. This leads to dry wall coking and results in low recovery rate of light components.

[0005] Furthermore, to improve the separation rate of residues, existing distillation systems often require an external high-temperature vacuum forced circulation pump to achieve repeated distillation of the material. External pumping of high-viscosity, high-temperature materials not only significantly increases the system's energy consumption and pipeline complexity, but the circulation pump itself also faces severe challenges related to mechanical seals and high failure rates. Summary of the Invention

[0006] To address the aforementioned problems, this application provides a self-circulating thin-film distillation apparatus and method that effectively improves the heat transfer rate and evaporation rate of high-viscosity materials.

[0007] To achieve the above objectives, in a first aspect, embodiments of this application provide a self-circulating thin-film distillation apparatus, comprising: The main body of the equipment, from top to bottom, includes an upper end cap, a cylinder and a lower end cap connected in sequence; the upper end cap forms a gas-liquid separation chamber inside, and the upper end cap has a gas phase outlet communicating with the gas-liquid separation chamber; An inner tube is vertically installed inside the cylinder. Both the top and bottom ends of the inner tube are open, and the outer wall of the inner tube is spaced from the inner wall of the cylinder to form a material return annular gap. A heat transfer medium sleeve assembly is disposed in the internal cavity of the inner tube. The heat transfer medium sleeve assembly includes multiple vertically arranged heating sleeves, each of which includes a coaxially nested outer sleeve and an inner sleeve. The material inlet connects to the interior of the lower part of the cylinder; The stripping inlet has its pipeline inserted into the lower part of the main body of the equipment, and the release end of the stripping inlet is located at or below the bottom opening of the inner pipe. The gas-liquid separation chamber is provided with a bowl-shaped end cap with its concave surface facing downwards and directly opposite the top opening of the inner tube. The maximum outer diameter of the bowl-shaped end cap is larger than the outer diameter of the top opening of the inner tube. A flow gap is formed between the edge of the bowl-shaped end cap and the inner wall of the gas-liquid separation chamber and the top opening of the inner tube, so that the gas-liquid mixture rising through the inner tube will separate after impacting the bowl-shaped end cap: the gas phase fluid enters the gas-liquid separation chamber upwards through the flow gap; the unvaporized liquid phase fluid is guided outwards along the surface of the bowl-shaped end cap and falls back into the material return annular gap through the flow gap.

[0008] Preferably, the inner tube is further provided with a number of support baffles fixed at staggered intervals along the vertical direction. Each heating sleeve is vertically inserted through each of the support baffles and is provided with lateral positioning support. Adjacent upper and lower support baffles are staggered left and right inside the inner tube, and the orthographic projections of the adjacent upper and lower support baffles on the horizontal plane complement each other, forming a complete cross-section that matches the cross-section of the inner tube cavity. The support baffles are used to block and change the flow direction of the fluid inside the inner tube, forcing the upward-flowing material and gas-liquid mixture to rise in an S-shaped reversal path inside the inner tube.

[0009] Preferably, a partition is horizontally fixed inside the lower end cap, dividing the interior of the lower end cap into a first chamber located above and a second chamber located below the first chamber; the top end of the outer sleeve is closed, and the bottom end of the outer sleeve is fixed to the top of the first chamber and communicates with the interior of the first chamber; the top end of the inner sleeve is open and located in the inner cavity of the outer sleeve, and the bottom end of the inner sleeve passes downward through the partition and communicates with the second chamber; wherein, a heat medium inlet communicating with the first chamber is opened on the side wall of the lower end cap, and a heat medium outlet communicating with the second chamber is opened at the bottom or lower part of the side wall of the lower end cap.

[0010] Preferably, the lower end cap is provided with a drain port communicating with the first chamber on its side wall, and the drain port is located at the lowest point of the bottom surface inside the first chamber.

[0011] Preferably, the lower part of the main body of the device is provided with an exhaust port that communicates with the first chamber.

[0012] Preferably, the bowl-shaped end cap is a semi-elliptical curved shell or a hemispherical curved shell, and the outer wall of the bowl-shaped end cap is fixedly connected to the inner wall of the upper end cap by a number of supports.

[0013] Preferably, the material inlet extends into the cylinder to form a feed pipe, and the end of the feed pipe is provided with an arc-shaped guide pipe, the opening direction of the end of the arc-shaped guide pipe being offset from the radial centerline of the cylinder.

[0014] Preferably, the outer wall of the inner tube is provided with a plurality of positioning brackets distributed circumferentially, and the inner tube is fixed to the inner wall of the cylinder by the positioning brackets, so that the radial width of the material return annular gap remains consistent.

[0015] Preferably, a residual liquid outlet is provided on the lower side wall of the upper end cap, the top opening of the inner tube extends into the upper end cap, and the vertical height of the top opening of the inner tube is higher than the vertical height of the residual liquid outlet.

[0016] Secondly, embodiments of this application provide a method for performing thin-film distillation using the self-circulating thin-film distillation apparatus described in any embodiment of the first aspect, comprising the following steps: S1: The heat medium is introduced into the heat medium jacket assembly and circulates between the outer and inner jackets of each heating jacket to provide continuous heat for the distillation process. S2: The material to be distilled is introduced into the lower part of the cylinder through the material inlet, and the stripping gas is released into the material through the stripping inlet at or below the bottom of the inner tube; S3: The material is heated on the outer wall of the heating sleeve inside the inner tube, and the light components are heated and vaporized. The gas produced by vaporization and the released stripping gas flow upward together in the inner tube. The carrying force generated by the upward movement of the gas phase fluid drives the unvaporized liquid phase material to move upward along the outer wall of each heating sleeve and form a thin film for contact distillation. S4: The gas-liquid mixture that has completed distillation rushes upward out of the top opening of the inner tube and impacts the concave surface of the bowl-shaped head to dissipate kinetic energy and separate: the separated gas phase fluid bypasses the bowl-shaped head, enters the gas-liquid separation chamber upward through the flow gap, and is finally discharged from the gas phase outlet. S5: The unvaporized heavy component liquid fluid after impact is blocked by the bowl-shaped head, flows outward along the surface of the bowl-shaped head, and falls back into the material return annular gap through the flow gap; the liquid fluid entering the material return annular gap falls vertically to the bottom of the cylinder under its own gravity, mixes with the newly introduced material to be distilled, and then enters the bottom of the inner tube again.

[0017] The self-circulating thin-film distillation equipment and method designed in this application utilizes an inner tube guiding structure combined with nested heat medium tube bundles and a bowl-shaped head to achieve unpowered internal circulation by leveraging the upward force of gas lift and gravity during the material vaporization process. This scheme eliminates mechanical rotating parts and external circulation pumps, thus eliminating dynamic seal failure points under high-temperature and high-vacuum conditions. The staggered arrangement of the supporting baffles guides the fluid to rise along a zigzag path within the inner tube, increasing heating time and fluid turbulence, thereby improving the heat transfer rate and evaporation rate of high-viscosity materials. The bowl-shaped head, in conjunction with the material reflux annular gap, establishes a defined gas-liquid separation and reflux path, reducing system energy consumption and preventing coking of high-viscosity materials on the heated surface. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the planar structure of the self-circulating thin-film distillation apparatus provided in the embodiments of this application.

[0019] Figure 2 yes Figure 1 Enlarged diagram of point A in the middle.

[0020] Figure 3 This is a schematic diagram of the arrangement of the partitions provided in the embodiments of this application.

[0021] Figure 4 This is a top view of the upper end cap provided in an embodiment of this application.

[0022] Figure 5 yes Figure 1 Sectional view at point BB.

[0023] Figure 6 This is a schematic diagram showing the location of the stripping inlet provided in an embodiment of this application.

[0024] The equipment includes: main body 100, cylinder 10, first support 11, temperature gauge port 12, manhole 13, sight glass 14, reinforcing rib 15, upper end cap 20, gas-liquid separation chamber 21, bowl-shaped end cap 22, flow gap 222, second support 23, vent 24, lower end cap 30, partition 31, first chamber 311, second chamber 312, inner tube 40, material return annular gap 50, heat medium sleeve assembly 60, heating sleeve 61, outer sleeve 611, inner sleeve 612, fixed support plate 613, supporting baffle plate 70, steam tracing device 80, heat medium outlet N1, heat medium inlet N2, material inlet N3, gas phase outlet N4, stripping inlet N5, residual liquid outlet N6, steam tracing inlet N9, condensate outlet N10, exhaust port N12, and liquid outlet N13. Detailed Implementation

[0025] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0026] In a first aspect, embodiments of this application provide a self-circulating thin-film distillation apparatus, which mainly consists of an apparatus body 100. For example... Figure 1 As shown, the main body 100 of the device is a vertical sealed container, which includes an upper head 20, a cylindrical body 10, and a lower head 30 connected sequentially from top to bottom. The upper head 20 has a gas-liquid separation chamber 21 for collecting gas, and a gas phase outlet N4 communicating with the gas-liquid separation chamber 21 is provided on the upper head 20 to allow the separated light component gas to be discharged to the subsequent condensation system. In this embodiment, the upper head 20 is also provided with an vent 24 to meet the needs of vacuum distillation.

[0027] An inner tube 40 is vertically installed inside the cylinder 10. Both the top and bottom of the inner tube 40 are open. To ensure structural stability and flow uniformity, several first supports 11 are distributed circumferentially on the outer wall of the inner tube 40, and the inner tube 40 is firmly fixed to the inner wall of the cylinder 10 by the first supports 11. This arrangement creates a regular material return annular gap 50 between the outer wall of the inner tube 40 and the inner wall of the cylinder 10, and the first supports 11 ensure that the radial width of the material return annular gap 50 remains consistent, thereby ensuring that the unvaporized material can descend and return uniformly and smoothly under gravity.

[0028] The inner cavity of the inner tube 40 houses a heat transfer medium sleeve assembly 60, which serves as a heating component. The heat transfer medium sleeve assembly 60 includes multiple vertically arranged heating sleeves 61, each of which includes a coaxially nested outer sleeve 611 and an inner sleeve 612. To achieve physical isolation and uniform distribution of the heat transfer medium, such as heat transfer oil, a partition 31 is horizontally fixed inside the lower end cap 30. The partition 31 divides the interior of the lower end cap 30 into a first chamber 311 located above and a second chamber 312 located below the first chamber 311.

[0029] In this embodiment, as Figure 1 , Figure 2 As shown, in terms of the structural arrangement and connection of the heat medium pipeline, each heating sleeve presents a coaxial nested structure of a large tube inside a small tube. Specifically, the top of the outer sleeve 611 is closed, and the bottom of the outer sleeve 611 is fixed to the top of the first chamber 311 and communicates with the internal space of the first chamber 311; the top of the inner sleeve 612 is open and suspended in the inner cavity of the outer sleeve 611, thereby forming a narrow annular flow channel radially spaced between the outer wall of the inner sleeve 612 and the inner wall of the outer sleeve 611. The bottom of the inner sleeve 612 passes downward through the partition 31 and communicates with the second chamber 312. By adopting this nested spatial arrangement of a large tube inside a small tube, when the high-temperature heat medium enters the above-mentioned annular flow channel and flows from bottom to top, due to the narrow channel cross-section, the heat medium can be fully spread on the inner wall surface of the outer sleeve 611 and forced to form a flowing heat medium liquid film. Based on the aforementioned fluid distribution pattern of the material to be distilled climbing upwards onto the film outside the outer casing 611 under the influence of airflow, this structure allows for the formation of a heat transfer medium liquid film and a distillate liquid film on both the inner and outer sides of the core heating wall of the outer casing 611, respectively. This double-sided thin-film, close-range heat exchange mode effectively eliminates the boundary layer thermal resistance within the fluid, maximizing the effective contact heating area between the heat transfer medium and the cold transfer medium within a limited equipment volume. This enables the heat transfer medium liquid film inside the tube and the distillate liquid film outside the tube to achieve a very high-flux heat transfer coupling effect through the tube wall, thereby effectively improving the overall heat transfer coefficient and material evaporation rate of the equipment, and significantly reducing the operating energy consumption of the system's heat source and the circulation and operating costs of the material and heat transfer medium during the processing cycle.

[0030] In other embodiments, a hemispherical fixed support plate 613 is provided between the outer sleeve 611 and the inner sleeve 612. The fixed support plate 613 is used to ensure that the annular flow channel gap between the outer sleeve 611 and the inner sleeve 612 is uniform. In specific implementation, the fixed support plate 613 can be arranged in several layers along the vertical direction of the inner sleeve 612, for example, four layers. Each layer has three fixed support plates 613 arranged at 120-degree intervals, and the fixed support plates 613 of adjacent upper and lower layers are staggered by 180 degrees to reduce disturbance to the flowing medium.

[0031] To complement the aforementioned nested loop structure with physical isolation between two chambers, such as Figure 3 As shown, a heat medium inlet N2 communicating with the first chamber 311 is provided on the side wall of the lower end cap 30, and a heat medium outlet N1 communicating with the second chamber 312 is provided at the bottom or lower part of the side wall of the lower end cap 30. Under normal operation or shutdown maintenance conditions, in order to ensure that there is no residual heat medium inside the chamber and to avoid cross-contamination of materials, a drain port N13 communicating with the first chamber 311 is additionally provided on the side wall of the lower end cap 30. The drain port N13 is precisely located at the lowest point of the space inside the bottom surface of the first chamber 311 to meet the requirements of gravity-driven drainage. At the same time, an exhaust port N12 communicating with the first chamber 311 is provided at the lower part of the main body 100. This is used to completely empty the non-condensable gas remaining in the pipeline and chamber during the initial injection of heat medium into the system, thereby preventing the local gas resistance effect from destroying the continuous forming state of the heat medium liquid film on the inner wall. In practice, the exhaust port N12 is located at the bottom of the cylinder 10, and the bottom of the cylinder 10 has a certain thickness, on which the exhaust port N12 is located.

[0032] In some embodiments, such as Figure 1 , Figure 5 As shown, to enhance heating and mass transfer and provide tube bundle support, several support baffles 70 are fixed vertically and alternately inside the inner tube 40. Each heating sleeve 61 is vertically inserted through each support baffle 70 and is provided with lateral positioning support, thereby effectively preventing the slender heating sleeve 61 from deforming or vibrating under fluid scouring. Adjacent upper and lower support baffles 70 are staggered left and right inside the inner tube 40, and the orthographic projections of adjacent upper and lower support baffles 70 on the horizontal plane complement each other, forming a complete cross-section that matches the cross-section of the inner tube 40. In this arrangement, the support baffles 70 are used to block and change the straight flow direction of the fluid inside the inner tube 40, forcing the upward-flowing material and gas-liquid mixture to rise in an S-shaped bend within the inner tube 40, effectively increasing the residence time of the material in the heated area and reducing local turbulent disturbances in the fluid.

[0033] In some embodiments, such as Figure 1 , Figure 3 As shown, in terms of material input, the equipment is equipped with a material inlet N3 that connects to the lower interior of the cylinder 10. Specifically, the material inlet N3 extends into the cylinder 10 to form a feed pipe, and the end of the feed pipe is provided with an arc-shaped guide pipe. The opening direction of the end of the arc-shaped guide pipe is offset from the radial centerline of the cylinder 10. This non-direct-flow tangential feeding structure can effectively prevent the high-speed material flow from directly impacting the core heating sleeve 61. A stripping inlet N5 is also inserted into the lower part of the equipment body 100, and the release end of the stripping inlet N5 is located at or below the bottom opening of the inner pipe 40, used to inject steam or inert gas to reduce the partial pressure of light components in the system.

[0034] In some embodiments, such as Figure 1 , Figure 2 As shown, in terms of gas-liquid separation and circulation, the gas-liquid separation chamber 21 is equipped with a bowl-shaped end cap 22 with its concave surface facing downwards and directly opposite the top opening of the inner tube 40. The bowl-shaped end cap 22 is a semi-elliptical curved shell or a hemispherical curved shell, and its outer side wall is fixedly connected to the inner wall of the upper end cap 20 by several second supports 23. The maximum outer diameter of the bowl-shaped end cap 22 is larger than the outer diameter of the top opening of the inner tube 40, and a specific space is reserved between the edge of the bowl-shaped end cap 22 and the inner wall of the gas-liquid separation chamber 21 and the top opening of the inner tube 40, thereby forming a flow gap 222. The top opening of the inner tube 40 extends upwards into the upper end cap 20, and a residual liquid outlet N6 is opened on the lower side wall of the upper end cap 20, and the vertical height of the top opening of the inner tube 40 is higher than the vertical height of the residual liquid outlet N6. This dimensional relationship causes the gas-liquid mixture that rises rapidly through the inner tube 40 to dissipate kinetic energy and undergo two-phase separation after impacting the bowl-shaped end cap 22. The separated gaseous fluid, due to its extremely low density, turns upward through the flow gap 222 and enters the gas-liquid separation chamber 21; the unvaporized heavy component liquid fluid flows outward along the smooth surface of the bowl-shaped head 22 and falls back accurately into the material return annular gap 50 through the flow gap 222. Finally, the accumulated residue that does not participate in the circulation can be discharged from the residual liquid outlet N6.

[0035] In some embodiments, such as Figure 1 As shown, multiple temperature gauge ports 12 are longitudinally spaced along the vertical height of the cylinder 10. These ports 12 are linearly arranged and penetrate the wall of the cylinder 10, serving to mount temperature sensing elements such as resistance temperature detectors (RTDs) or thermocouples. Because the high-viscosity material processed in this application is highly heat-sensitive, by setting multiple temperature detection points at different heights in the heated section, the temperature gradient data of the liquid film inside the material reflux annular gap 50 at different phase transition stages can be obtained in real time. This monitoring and feedback mechanism provides data support for adjusting the external heating medium temperature and optimizing the stripping gas volume in real time, effectively preventing local overheating and coking of the material, and ensuring that the extraction rate of light components is at its optimal condition.

[0036] like Figure 1 , Figure 2As shown, a maintenance and observation structure is integrated on the upper end cap in the top region of the main body of the equipment. A manhole 13 is provided on the side or top of the upper end cap, extending outward along its axis and equipped with a sealing cover. The diameter of the manhole 13 is sufficient for technicians to enter or tools to be inserted, and its main function is to provide maintenance access for key separation components such as the bowl-shaped end cap 22 and the top opening of the inner tube 40 inside the equipment. During equipment shutdown for cleaning or periodic maintenance, operators can directly clean scale or residue inside the gas-liquid separation chamber 21 through the manhole 13, thereby ensuring the long-term stability of gas-liquid separation efficiency.

[0037] In addition, such as Figure 2 As shown, a sight glass 14 is also embedded in the wall of the upper end cap 20. The orthogonal projection direction of the sight glass 14 faces the flow gap 222 between the bowl-shaped end cap 22 and the top opening of the inner tube 40. Under high vacuum operating conditions, the operator can observe in real time the physical process of the gas-liquid mixture rushing out of the inner tube 40 and impacting the bowl-shaped end cap 22 through the sight glass 14, thereby intuitively judging the morphology of the gas-climbing film, the continuity of liquid phase reflux, and the bursting state of bubbles. The sight glass 14 enables visual monitoring of the internal invisible fluid dynamics process, providing a visual basis for calibrating process parameters when the equipment processes materials of different viscosities.

[0038] In some embodiments, such as Figure 1 As shown, several reinforcing ribs 15 are provided between the cylinder 10 and the upper end cap 20 to ensure the connection strength of the overall structure.

[0039] In a further embodiment, in order to ensure the fluidity of high-viscosity materials within the material reflux annular gap 50 and reduce heat loss, a steam tracing device 80 is provided on the outer wall of the cylinder 10.

[0040] Specifically, the steam tracing device 80 includes a semi-tubular heat tracing jacket welded to the outer wall of the cylinder 10. The semi-tubular heat tracing jacket is formed by continuously spirally winding multiple semi-circular cross-section pipes along the axial direction of the cylinder 10. The edges of the pipes are sealed to the outer surface of the cylinder 10, thereby forming a closed spiral heat tracing channel on the outer wall of the cylinder 10. The upper part of the semi-tubular heat tracing jacket has a steam tracing inlet N9, and the lower part has a condensate outlet N10. Heating steam enters the spiral heat tracing channel through the steam tracing inlet N9, and the heat is conducted through the wall of the cylinder 10 to the interior of the material return annular gap 50 to compensate for the temperature of the returned material.

[0041] Secondly, embodiments of this application provide a method for performing thin-film distillation using the self-circulating thin-film distillation apparatus described in any embodiment of the first aspect, comprising the following steps: In step S1, an external heat source introduces a high-temperature heat transfer medium into the heat transfer medium sleeve assembly 60. After entering the first chamber 311 through the heat transfer medium inlet N2, the heat transfer medium is distributed upwards into each outer sleeve 611, flowing upwards within the annular channel formed between the outer sleeve 611 and the inner sleeve 612 of each heating sleeve. Upon reaching the closed top, the heat transfer medium reverses direction, flowing downwards through the inner sleeve 612 to the second chamber 312 and exiting through the heat transfer medium outlet N1. The path of the heat transfer medium is an inverted U-shape, forming a heat transfer medium film between the outer sleeve 611 and the inner sleeve 612. This cyclical flow process provides stable and continuous heat to the evaporator tube wall.

[0042] In the feeding and stripping step S2: The high-viscosity material to be distilled is smoothly introduced into the liquid pool at the bottom of the cylinder 10 through the material inlet N3 and the arc-shaped guide pipe. At the same time, stripping gas with a certain pressure is continuously released into the mixture through the stripping inlet N5 at or below the bottom of the inner tube 40.

[0043] Step S3, involving vaporization and distillation, involves the material being heated directly in contact with the outer wall of the heating sleeve 61 inside the inner tube 40. A large amount of the low-boiling-point light components are vaporized. Due to the limited space in the inner tube 40, the vaporized gas mixes with the stripping gas released from the bottom within the inner tube 40 and flows upward at high speed. This upward movement of the gaseous fluid generates a strong airflow carrying force, overcoming gravity and viscosity, driving the unvaporized high-viscosity liquid material upward along the outer wall of each heating sleeve 61 and stretching it to form an extremely thin liquid film for efficient contact distillation. During this film-climbing process, the fluid is forced to rise in an S-shaped reversal path by the supporting baffle 70, further amplifying the mass transfer efficiency. In this step, the material, i.e., the refrigerant, forms a refrigerant film between the inner tube 40 and the outer sleeve 611. Both the cold and hot media can form films, achieving a double-film evaporation mode. This fully utilizes the distillation contact surface and the heat of the hot media, resulting in high thermal efficiency and reducing the evaporation surface area, thus saving on equipment investment costs.

[0044] The impact separation step S4 is performed: the violently mixed gas-liquid fluid that has completed endothermic distillation rushes upward out of the top opening of the inner tube 40, and then impacts the concave surface of the bowl-shaped end cap 22 directly above it at high speed. The impact causes effective kinetic energy dissipation and phase separation. The separated gaseous light component fluid bypasses the edge of the bowl-shaped end cap 22, flows upward through the flow gap 222 and enters the gas-liquid separation chamber 21, and is finally discharged from the equipment through the gas phase outlet N4 at the top for cooling and recovery.

[0045] In step S5, gravity reflux and self-circulation are performed: The liquid fluid, including heavy, sticky residue that has lost upward kinetic energy after impact and has not yet vaporized, is physically blocked by the bowl-shaped head 22 shell and cannot enter the upper space. It can only flow smoothly outward along the curved surface of the bowl-shaped head 22, and then directionally fall back into the outer material reflux annular gap 50 through the flow gap 222. Since there is no upward airflow and the fluid density is high within the material reflux annular gap 50, the liquid fluid entering this gap falls vertically down the inner wall of the cylinder 10 under its own gravity to the bottom of the cylinder 10, mixes with the newly introduced material to be distilled, and is then drawn back into the inner tube 40 from the bottom. The system achieves continuous and stable fluid circulation without the need for an external mechanical pump, relying on the ingenious layout of its internal components.

[0046] The self-circulating thin-film distillation equipment and method provided in this application utilizes an inner tube guiding structure combined with nested heat medium tube bundles and a bowl-shaped head to achieve unpowered internal circulation by leveraging the upward force of gas lift and gravity during material vaporization. This scheme eliminates mechanical rotating parts and external circulation pumps, thus eliminating dynamic seal failure points under high-temperature and high-vacuum conditions. The staggered arrangement of the supporting baffles guides the fluid to rise along a zigzag path within the inner tube, increasing heating time and fluid turbulence, thereby improving the heat transfer rate and evaporation rate of high-viscosity materials. The bowl-shaped head, in conjunction with the material reflux annular gap, establishes a defined gas-liquid separation and reflux path, reducing system energy consumption and preventing dry-wall coking of high-viscosity materials on the heating surface.

[0047] In the description of this application, it should be noted that the terms "vertical", "up", "down", "horizontal", 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 application 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 application.

[0048] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" 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; 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 application according to the specific circumstances.

[0049] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A self-circulating thin film distillation apparatus, characterized by, include: The main body of the equipment, from top to bottom, includes an upper end cap, a cylinder and a lower end cap connected in sequence; the upper end cap forms a gas-liquid separation chamber inside, and the upper end cap has a gas phase outlet communicating with the gas-liquid separation chamber; An inner tube is vertically installed inside the cylinder. Both the top and bottom ends of the inner tube are open, and the outer wall of the inner tube is spaced from the inner wall of the cylinder to form a material return annular gap. A heat transfer medium sleeve assembly is disposed in the internal cavity of the inner tube. The heat transfer medium sleeve assembly includes multiple vertically arranged heating sleeves, each of which includes a coaxially nested outer sleeve and an inner sleeve. The material inlet connects to the interior of the lower part of the cylinder; The stripping inlet has its pipeline inserted into the lower part of the main body of the equipment, and the release end of the stripping inlet is located at or below the bottom opening of the inner pipe. The gas-liquid separation chamber is provided with a bowl-shaped end cap with its concave surface facing downwards and directly opposite the top opening of the inner tube; the maximum outer diameter of the bowl-shaped end cap is larger than the outer diameter of the top opening of the inner tube; a flow gap is formed between the edge of the bowl-shaped end cap and the inner wall of the gas-liquid separation chamber and the top opening of the inner tube, so that the gas-liquid mixture rising through the inner tube will separate after impacting the bowl-shaped end cap: the gas phase fluid enters the gas-liquid separation chamber upwards through the flow gap; Unvaporized liquid fluid flows outward along the surface of the bowl-shaped head and falls back into the material return annular gap through the flow gap.

2. The self-circulating thin film distillation apparatus according to claim 1, wherein, The inner tube is also equipped with several vertically staggered support baffles. Each heating sleeve is vertically inserted through each support baffle and is provided with lateral positioning support. Adjacent upper and lower support baffles are staggered left and right inside the inner tube, and the orthographic projections of the adjacent upper and lower support baffles on the horizontal plane complement each other, forming a complete cross-section that matches the cross-section of the inner tube cavity. The support baffles are used to block and change the flow direction of the fluid inside the inner tube, forcing the upward-flowing material and gas-liquid mixture to rise in an S-shaped reversal path inside the inner tube.

3. The self-circulating thin film distillation apparatus according to claim 1, wherein, A partition is horizontally fixed inside the lower end cap, dividing the interior of the lower end cap into a first chamber located above and a second chamber located below the first chamber. The top end of the outer sleeve is closed, and the bottom end of the outer sleeve is fixed to the top of the first chamber and communicates with the interior of the first chamber. The top end of the inner sleeve is open and located in the inner cavity of the outer sleeve, and the bottom end of the inner sleeve passes downward through the partition and communicates with the second chamber. A heat medium inlet communicating with the first chamber is opened on the side wall of the lower end cap, and a heat medium outlet communicating with the second chamber is opened at the bottom or lower part of the side wall of the lower end cap.

4. The self-circulating thin film distillation apparatus according to claim 3, wherein, The lower end cap is also provided with a drain port that communicates with the first chamber on its side wall, and the drain port is located at the lowest point of the bottom surface inside the first chamber.

5. The self-circulating thin film distillation apparatus according to claim 3, wherein, The lower part of the main body of the device is provided with an exhaust port that communicates with the first chamber.

6. The self-circulating thin film distillation apparatus according to claim 1, wherein, The bowl-shaped end cap is a semi-elliptical curved shell or a hemispherical curved shell, and the outer wall of the bowl-shaped end cap is fixedly connected to the inner wall of the upper end cap through several supports.

7. The self-circulating thin film distillation apparatus according to claim 1, wherein, The material inlet extends into the cylinder to form a feed pipe, and the end of the feed pipe is provided with an arc-shaped guide pipe. The opening direction of the end of the arc-shaped guide pipe is offset from the radial center line of the cylinder.

8. The self-circulating thin film distillation apparatus according to claim 1, wherein, The outer wall of the inner tube is provided with several positioning brackets distributed circumferentially. The inner tube is fixed to the inner wall of the cylinder by the positioning brackets, so that the radial width of the material return annular gap remains consistent.

9. The self-circulating thin film distillation apparatus according to claim 1, wherein, The lower side wall of the upper end cap is provided with a residual liquid outlet, the top opening of the inner tube extends into the upper end cap, and the vertical height of the top opening of the inner tube is higher than the vertical height of the residual liquid outlet.

10. A method for performing thin film distillation using the self-circulating thin film distillation apparatus according to any one of claims 1 to 9, characterized by, Includes the following steps: S1: The heat medium is introduced into the heat medium jacket assembly and circulates between the outer and inner jackets of each heating jacket to provide continuous heat for the distillation process. S2: The material to be distilled is introduced into the lower part of the cylinder through the material inlet, and the stripping gas is released into the material through the stripping inlet at or below the bottom of the inner tube; S3: The material is heated on the outer wall of the heating sleeve inside the inner tube, and the light components are heated and vaporized. The gas produced by vaporization and the released stripping gas flow upward together in the inner tube. The carrying force generated by the upward movement of the gas phase fluid drives the unvaporized liquid phase material to move upward along the outer wall of each heating sleeve and form a thin film for contact distillation. S4: The gas-liquid mixture that has completed distillation rushes upward out of the top opening of the inner tube and impacts the concave surface of the bowl-shaped head to dissipate kinetic energy and separate: the separated gas phase fluid bypasses the bowl-shaped head, enters the gas-liquid separation chamber upward through the flow gap, and is finally discharged from the gas phase outlet. S5: The unvaporized heavy component liquid fluid after impact is blocked by the bowl-shaped head, flows outward along the surface of the bowl-shaped head, and falls back into the material return annular gap through the flow gap; the liquid fluid entering the material return annular gap falls vertically to the bottom of the cylinder under its own gravity, mixes with the newly introduced material to be distilled, and then enters the bottom of the inner tube again.

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