Multi-pass spiral plate high-precision rectifying device and rectifying process

Abstract

The application discloses a multi-channel spiral plate type high-precision rectifying device and a rectifying process, relates to the field of boiling circulating rectification, and comprises a rectifying tank cylinder, a central support main pipe, a low-speed rotating driving mechanism, a tower top defoaming condensing collecting unit and a circulating reboiling unit. The upper and lower ends of the rectifying tank cylinder are fixedly provided with sealing components. The central support main pipe is rotationally clamped at the central positions of the two sealing components. The sealing components are used for realizing the rotating sealing of the central support main pipe. The device is provided with a spiral mass transfer component, a flow guide short pipe in communication between the first spiral mass transfer inner part and the second spiral mass transfer inner part, and forced liquid phase descending along the spiral long path, so that the liquid phase vertical short circuit is completely eliminated. The liquid phase short circuit rate of the traditional single-layer spiral plate is more than 60%, the liquid phase short circuit rate of the device is less than 8%, the effective gas-liquid contact time is increased by 2.1-2.8 times, the processing capacity is higher under the same tower diameter, and the purification efficiency is also simultaneously improved.

Description

Technical Field

[0001] This invention relates to the field of boiling cycle distillation, specifically to a multi-channel spiral plate high-precision distillation device and distillation process. Background Technology

[0002] N-Methylpyrrolidone (NMP) is a highly selective and stable polar aprotic solvent with a boiling point of 202℃ (at ambient pressure). It possesses advantages such as low toxicity, strong dissolving power, and non-flammability, and is widely used in lithium-ion battery electrode coating, semiconductor photoresist manufacturing, aromatic hydrocarbon extraction, and pharmaceutical intermediate production. However, NMP is prone to thermal decomposition and polymerization reactions at high temperatures, affecting product purity and yield. Therefore, the distillation purification of NMP typically requires high vacuum and low temperature conditions. The distillation column is the core equipment for achieving gas-liquid separation. Traditional plate columns (such as sieve tray columns and valve tray columns) and packed columns face several technical bottlenecks when applied to high-vacuum low-temperature distillation. First, the plate spacing in plate columns is usually large (traditional sieve tray column plate spacing is generally 300-600 mm), resulting in a large overall column height and high pressure drop. Under high vacuum conditions, a large overall column pressure drop means that the reboiler must maintain a higher operating temperature to provide sufficient mass transfer driving force, which exacerbates the thermal decomposition of NMP. Secondly, although structured packings have a lower pressure drop (approximately 0.3-1.0 kPa / m), their theoretical plate equivalent height (HETP) is typically 0.2-0.4 m. For separation tasks requiring a high theoretical plate number, the packing layer height is still relatively large.

[0003] In recent years, researchers have attempted to reduce column height and pressure drop by decreasing the plate spacing. However, the reduction of plate spacing is limited by the flooding limit: when the plate spacing is too small, the phenomenon of gas entrainment of liquid droplets intensifies dramatically, the gas-liquid flux decreases significantly, and the tray cannot operate normally. Furthermore, with a smaller plate spacing, the gas-liquid contact time and contact area also decrease, leading to a decline in mass transfer efficiency. Therefore, traditional trays face a sharp contradiction between "miniaturization" and "efficiency improvement"—the smaller the plate spacing, the more limited the flux and the worse the mass transfer efficiency, creating a technological paradox. In summary, existing spiral plate distillation columns and plate distillation equipment have the following inherent defects: Single-layer plate towers lack a forced flow guiding structure, resulting in over 60% vertical short-circuit descent of the liquid phase. This leads to a short effective gas-liquid contact path, poor mass transfer efficiency, and lower throughput and purification accuracy for the same tower diameter. Traditional plate towers employ multi-layer horizontal plates and downcomers, enabling segmented gas-liquid mass transfer. However, they suffer from significant structural shortcomings: short mass transfer paths, insufficient gas-liquid contact, low single-pass separation efficiency, and difficulty in achieving ultra-high purity material purification. Packed towers rely on packing to create mass transfer area, suitable for low-pressure-drop conditions, but their adaptability is extremely poor. The small and dense packing gaps easily clog and clump materials containing impurities or prone to crystallization, and there are many internal dead zones, making cleaning difficult, resulting in high consumable replacement costs and significant downtime losses. They also suffer from severe wall flow effects, uneven liquid phase distribution, strong randomness in gas-liquid mass transfer, and poor purification stability. Lacking forced flow guiding and circulating mass transfer structures, they have a low upper limit for purification accuracy. High-viscosity and high-impurity materials easily cause packing collapse and flow channel turbulence, making them unsuitable for long-term high-temperature continuous distillation conditions.

[0004] In summary, existing distillation units, due to their single-layer plate structure and lack of forced flow guidance between layers, suffer from inherent defects such as severe vertical short-circuiting of the liquid phase, short effective gas-liquid contact paths, low mass transfer efficiency, and relatively low throughput and purification accuracy for the same column diameter. They also face technical challenges such as insufficient upper limit of separation purity, poor stability during long-axis operation, easy sieve clogging, and high energy consumption in multi-stage distillation, making them unsuitable for continuous high-precision distillation operations in high-end fine chemicals, pharmaceutical raw materials, and electronic-grade solvents. Therefore, there is an urgent need to develop a novel spiral plate high-precision distillation unit that can effectively solve the problem of vertical short-circuiting of the liquid phase and significantly improve gas-liquid mass transfer efficiency and separation accuracy. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-channel spiral plate high-precision distillation device and distillation process to solve the problems mentioned in the background art.

[0006] A multi-channel spiral plate high-precision distillation device and distillation process includes a distillation tank body, a central support main pipe, a low-speed rotation drive mechanism, a column top demister condenser and collection unit, and a circulating reboiler unit. Sealing components are fixedly installed at both the upper and lower ends of the distillation tank body. The central support main pipe is rotatably locked at the center position of the two sealing components. The sealing components are used to achieve rotational sealing of the central support main pipe. Multiple sets of evenly distributed spiral mass transfer components are fixedly installed on the central support main pipe. The spiral mass transfer components include a first spiral mass transfer inner element and a second spiral mass transfer inner element. A spiral gas phase interlayer channel is formed between the first spiral mass transfer inner element and the second spiral mass transfer inner element. A bottom gas phase inlet is provided on one side of the bottom end of the distillation tank body. The bottom gas phase inlet is connected to multiple gas phase interlayer channels.

[0007] Furthermore, the first and second helical mass transfer inner components are provided with multiple uniformly distributed guide grooves, and the first and second helical mass transfer inner components are also provided with multiple uniformly distributed mass transfer sieve holes. The mass transfer sieve holes and guide grooves are staggered. Multiple overflow weirs are fixedly installed on both the first and second helical mass transfer inner components. Multiple sets of guide short pipes are fixedly connected between the first and second helical mass transfer inner components, and the number of guide short pipes in each set is set to multiple. The guide short pipes penetrate through the first and second helical mass transfer inner components.

[0008] Furthermore, the sealing component includes a bearing protective cover, on the outside of which a rubber sealing sleeve is fitted. The bearing protective cover is embedded inside the distillation tank body. A connecting plate is fixedly installed on the side of the bearing protective cover away from the distillation tank body. A self-aligning bearing with a seat is fixedly installed on the connecting plate. The central support main pipe is rotatably locked in the middle of the self-aligning bearing. A nylon baffle is provided below the rubber sealing sleeve. A rotating shaft connecting block is provided below the nylon baffle. The central support main pipe passes through the bearing protective cover and the rubber sealing sleeve and is fixedly installed in the middle of the rotating shaft connecting block. The nylon baffle is fixedly installed on the bearing protective cover by countersunk screws. The nylon baffle tightly presses the rubber sealing sleeve against the outside of the bearing protective cover. A PTFE plus carbon fiber plug seal for increasing the sealing between the bearing protective cover and the central support main pipe is fixedly installed inside the bearing protective cover. A temperature sensor is fixedly installed on the connecting plate. The temperature sensor passes through the connecting plate, the rubber sealing sleeve, and the bearing protective cover and extends into the inside of the distillation tank body. A temperature sensor is also fixedly installed in the middle of the distillation tank body.

[0009] Furthermore, the low-speed rotary drive mechanism includes a double cross universal joint, a reducer, and an explosion-proof drive motor. One end of the double cross universal joint is engaged with the output end of the reducer, and the end of the double cross universal joint away from the reducer is engaged with a rotating shaft connecting block. The input end of the reducer is fixedly installed with the output end of the explosion-proof drive motor, and the explosion-proof drive motor is externally connected to a water-cooling component.

[0010] Furthermore, the top two sides of the distillation tank body are respectively provided with a top gas phase outlet and a top gas phase reflux port. Inside the distillation tank body, at positions corresponding to the top gas phase outlet and the top gas phase reflux port, gas phase perforation plate components are fixedly installed. The gas phase perforation plate component includes a sealing shell and a separation plate. The separation plate has multiple evenly distributed separation holes. The upper surface of the separation plate is treated with a laser surface treatment process to make it hydrophobic, and the lower surface of the separation plate is sprayed with a hydrophilic coating.

[0011] Furthermore, the external surface of the gas phase outlet at the top of the column is covered with an insulated pipe, a first shut-off valve is fixedly installed on the gas phase outlet at the top of the column, a demister is fixedly installed on the gas phase reflux port at the top of the column, a second shut-off valve is also fixedly installed on the gas phase reflux port at the top of the column, a bottom waste liquid outlet is provided on the side of the bottom gas phase inlet of the column, a solenoid valve is installed on the bottom waste liquid outlet, and a pneumatic regulating valve is installed on the bottom gas phase inlet of the column.

[0012] Furthermore, the circulating reboiler unit includes a condenser, a raw material preheater, a reboiler, a storage tank group, and a filter. The top gas phase reflux port is connected to the input end of the condenser via a pipeline. The output end of the condenser is connected to the input end of the reflux tank via a pipeline. The output end of the reflux tank is connected to the input end of the raw material preheater via a pipeline. The output end of the raw material preheater is connected in series with a pump body that drives material circulation. The output end of the pump body is connected to the input end of the filter via a pipeline. The output end of the filter is connected to the bottom gas phase inlet via a pipeline.

[0013] Furthermore, a reboiler for heating circulating gas is installed on the distillation tank body. The reboiler is located above the bottom gas phase inlet of the tower. The input end of the raw material preheater is also connected to the output end of the liquid storage tank group through a pipeline. The input end of the liquid storage tank group is fixedly connected to the insulation pipeline of the adjacent unit above. An inspection port is fixedly installed in the middle and lower part of the distillation tank body.

[0014] Furthermore, the pore size of the mass transfer sieve is 2-3 mm, and the pores are arranged in an equilateral triangle on the surface of the corresponding first and second spiral mass transfer inner components. The guide groove does not penetrate the first or second spiral mass transfer inner component; the guide groove is only located on the upper surface of the first and second spiral mass transfer inner components. An absolute pressure transmitter is fixedly installed at the top of the inside of the distillation tank body, and a differential pressure transmitter is installed on the distillation tank body. The positive pressure side of the differential pressure transmitter is connected to the bottom of the distillation tank body, and the negative pressure side of the differential pressure transmitter is connected to the top of the distillation tank body.

[0015] A distillation process employing a multi-channel spiral plate high-precision distillation apparatus includes the following steps: S1. Initial vaporization feed: The material is completely vaporized into gas and liquid phases through the circulating reboiling unit and enters the spiral gas phase interlayer channel from the bottom gas phase inlet of the tower, flowing from bottom to top along the spiral gas phase interlayer channel. S2, Reverse mass transfer separation: In the spiral gas phase interlayer channel, the vapor penetrates the mass transfer sieve holes on the first and second spiral mass transfer inner components and comes into reverse bubbling contact with the liquid phase on the plate surface. The liquid phase is forced to flow downward along the spiral slope through the guide tube connecting the first and second spiral mass transfer inner components. S3, Reflux purification and condensation: The gas phase carrying light components rises to the top of the tower and passes through the gas phase reflux port at the top of the tower. After the mist droplets and impurities are removed by the demister, the circulation pipeline valve is opened and the gas enters the condenser for complete liquefaction. The liquefied reflux liquid is collected in the reflux tank. S4. Closed-loop multiple-cycle purification: The reflux liquid is sent to the circulating reboiling unit to boil and vaporize again. The high-temperature steam is reintroduced into the gas phase inlet at the bottom of the tower to complete one cycle. The cycle is repeated 3-8 times to improve the purity of the material. S5. High-temperature multi-stage conveying without cooling: After the material purity meets the standard, the second shut-off valve is closed and the first shut-off valve is opened. The high-temperature liquid reflux liquid is directly sent into the lower-level distillation tank for high-temperature boiling and deep separation. S6. Continuous self-cleaning operation: The low-speed rotation drive mechanism continuously drives the spiral mass transfer component to rotate at low speed, disturbing the liquid film on the plate surface to inhibit crystallization and blockage. S7. After preheating, the NMP waste liquid is sent to the upper part of the distillation tank. Inside the distillation tank, the liquid spreads along the surfaces of multiple first and second helical mass transfer internals to form a liquid film. The operating pressure inside the distillation tank is controlled at 1 kPa-10 kPa, the operating temperature at the bottom of the distillation tank is 80℃-120℃, and the operating temperature at the top of the distillation tank is 40℃-80℃. S8. The single-plate pressure drop of the first and second helical mass transfer internal components is 50Pa-200Pa, the Meurveli efficiency of the single plate is 60%-85%, and the theoretical plate equivalent height is 0.05m-0.15m.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This device uses a spiral mass transfer component, with a short guide tube connecting the first and second spiral mass transfer components, to force the liquid phase to flow downward along the long spiral path, eliminating vertical short-circuiting of the liquid phase; the liquid phase short-circuiting rate of traditional single-layer spiral plates exceeds 60%, while the liquid phase short-circuiting rate of this device is <8%, increasing the effective gas-liquid contact time by 2.1-2.8 times, resulting in higher throughput for the same tower diameter, and the purification efficiency will also be improved accordingly; 2. Construct a complete closed-loop circulation system of top defoaming - condensation and collection - secondary reboiling - bottom gas phase inlet, allowing materials to be vaporized multiple times and undergo multi-layer gas-liquid mass transfer; the purity of the product after a single reflux of a traditional single-layer spiral column is up to 95%, while the purity of this device can reach over 99% after 5 cycles, increasing the purification limit by 4%, and can stably prepare ultra-high purity pharmaceutical and electronic grade organic solvents. 3. Traditional two-point support results in a radial offset of 3-5mm during long shaft operation; the present invention features a multi-point self-aligning combination support with top and bottom thrust, resulting in a radial offset of ≤0.3mm, with no eccentricity or scratches; the continuous operating life of the equipment is extended, significantly reducing the replacement and maintenance costs of bearings and spiral plates; 4. Laser-smoothed micropores combined with low-speed rotating spiral plates to disturb the liquid film and prevent clogging; traditional fixed packing plates require shutdown for cleaning every 22-25 days, while this invention uses reverse cutting airflow to reduce downtime losses and increase production line capacity; 5. Traditional transfer cooling and reheating processes increase energy consumption by 20%-25% in multi-stage processing; the dual-path switching pipeline of this invention enables high-temperature materials to be directly sent to the next stage tank without transfer, eliminating the need for repeated heating, and reducing the energy consumption of the entire multi-stage distillation system by 15%-22%; the elimination of transfer storage tanks significantly reduces the footprint of the complete set of equipment. 6. All parts in contact with materials are made of 316L stainless steel, which is resistant to corrosion by alcohols, esters and organic acids, and is suitable for the purification of various fine chemical and pharmaceutical raw materials; the side wall of the cylinder is equipped with a maintenance hand hole, which makes it convenient to clean the equipment and screen holes; the multi-point bearings are equipped with external grease nipples, which can add lubricating grease without opening the tank. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 Enlarged view of point A in the middle; Figure 3 This is a schematic diagram of the structure of the gas phase perforation plate component in this invention; Figure 4 This is a schematic diagram of the sealing component in this invention; Figure 5 This is a flowchart of the raw material recycling and reboiling process in this invention; Figure 6 This is a schematic diagram of the structure of the helical mass transfer component in this invention; Figure 7 This is a schematic diagram of the flow guide channel and mass transfer sieve holes in the present invention; Figure 8 This is a process flow diagram of the present invention.

[0018] In the diagram: 1. Distillation tank body; 2. Spiral mass transfer component; 3. Central support main pipe; 4. Sealing component; 5. Pneumatic regulating valve; 6. Top vapor outlet; 7. Top vapor reflux port; 8. Bottom vapor inlet; 9. Bottom waste liquid outlet; 11. Vapor perforation plate component; 12. Double cross universal coupling; 13. Reducer; 14. Explosion-proof drive motor; 15. Demister; 16. Inspection port; 17. Condenser; 18. Reflux tank; 19. Raw material preheater; 20. First spiral mass transfer internals; 21. Second spiral mass transfer internals; 22. Re- 23. Boiler; 24. Storage tank assembly; 45. Filter; 46. Bearing protective cover; 47. Rubber sealing sleeve; 48. Connecting plate; 49. PTFE and carbon fiber plug seal; 40. Self-aligning bearing with seat; 41. Temperature sensor; 42. Nylon baffle; 43. Rotary shaft connecting block; 64. Insulated pipe; 75. First shut-off valve; 86. Second shut-off valve; 97. Sealing housing; 18. Separation plate; 198. Separation hole; 109. Water-cooled component; 200. Flow guide groove; 201. Flow guide short pipe; 202. Overflow weir; 203. Mass transfer sieve hole. Detailed Implementation

[0019] 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, and 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.

[0020] Please see Figure 1-8 This invention provides a multi-path spiral plate high-precision distillation device, which is composed of six functional subsystems working together: a mass transfer and separation subsystem centered on the distillation tank body 1 and the spiral mass transfer component 2; a main shaft support and sealing subsystem centered on the central support main pipe 3 and the sealing component 4; a low-speed rotation drive subsystem centered on the double cross universal coupling 12, the reducer 13, and the explosion-proof drive motor 14; a column top defoaming, condensation, and collection subsystem centered on the vapor phase through-plate component 11, the demister screen 15, the condenser 17, and the reflux tank 18; a circulating reboiler and operating condition switching subsystem centered on the raw material preheater 19, the reboiler 22, the filter 24, and the dual-way shut-off valve group; and a process monitoring subsystem centered on the temperature sensor 46, the absolute pressure transmitter, and the differential pressure transmitter. Each subsystem is connected to the electrical signal via pipelines to jointly realize multiple closed-loop boiling and circulating distillation of the material. The following details each subsystem.

[0021] The mass transfer separation subsystem is the core of this unit for achieving gas-liquid separation, including the distillation tank body 1 and multiple sets of spiral mass transfer components 2 installed inside it. The distillation tank body 1 is a vertical pressure-bearing cylinder, welded from 316L stainless steel, with flanges at both ends connected to sealing components 4. A bottom gas inlet 8 is provided in the lower middle part of the side wall of the tank body, serving as a circulating feed channel for secondary reboiler steam. A bottom waste liquid outlet 9 is provided on the bottom of the tank body away from the bottom gas inlet 8, used to discharge the enriched heavy component residue. An inspection port 16 is provided on the lower middle side wall of the tank body for easy internal flushing and maintenance.

[0022] Please see Figure 2 and Figure 6 , Figure 7 The spiral mass transfer components 2 are fixedly installed on the outer wall of the central support main pipe 3, and multiple sets are evenly distributed along the axial direction. Each set of spiral mass transfer components 2 includes a first spiral mass transfer inner component 20 and a second spiral mass transfer inner component 21. The two plates are formed by parallel spiraling of 316L stainless steel thin plates with equal pitch and the same direction of rotation. The plate thickness is 1.5-3mm. A continuous spiral gas phase interlayer channel with a spacing of 15-30mm is formed between the two plates, and the spiral helix angle is 15°-30°. The inner ring edge of the two spiral plates is fully welded to the outer wall of the central support main pipe 3 for sealing. The outer edge is integrally formed with an annular overflow weir 203 with a weir height of 15-25mm, which is used to stabilize the thickness of the mass transfer liquid layer on the plate surface.

[0023] Multiple guide grooves 201 extending radially along the spiral are formed on the upper surfaces of both the first spiral mass transfer inner element 20 and the second spiral mass transfer inner element 21. The guide grooves 201 are recessed only on the upper surface and do not penetrate the plate body. The groove width is 0.5-3mm, guiding the liquid phase on the plate surface to flow orderly along the spiral slope. Through-type mass transfer sieve holes 204 are also uniformly formed on both plates. The mass transfer sieve holes 204 and the guide grooves 201 are staggered. The sieve holes have a diameter of 2-3mm and are arranged in an equilateral triangular array with a center-to-center distance of 12-16mm and an opening rate of 8%-12%. The mass transfer sieve holes 204 are processed by coaxial auxiliary processing with 355nm ultraviolet laser and 0.15-0.6MPa high-purity nitrogen gas, resulting in smooth cuts without oxidation and reducing the probability of crystal adhesion.

[0024] Multiple sets of interconnected flow guide tubes 202 are vertically welded in segments along the spiral radial direction between the first spiral mass transfer inner element 20 and the second spiral mass transfer inner element 21. Each set contains multiple short tubes with a diameter of φ8-12mm, arranged in a spiral pattern every 2-3 turns. The flow guide tubes 202 vertically penetrate the upper and lower plates, forcibly guiding the upper liquid phase to the lower plate surface. This allows the liquid phase to slowly descend layer by layer along the spiral slope, rather than short-circuiting and falling vertically through the mass transfer sieve holes 204. As a result, the liquid phase short-circuit rate is reduced from over 60% in the traditional structure to below 8%, and the effective gas-liquid contact time is increased by 2.1-2.8 times.

[0025] Please see Figure 4The main shaft support sealing subsystem includes a central support main pipe 3 and two sets of sealing components 4 installed at the upper and lower ends of the distillation tank body 1, respectively. The sealing components 4 consist of a bearing protective cover 41, a rubber sealing sleeve 42, a connecting plate 43, a PTFE-coated carbon fiber plug seal 44, a self-aligning bearing with a mounting plate 45, a temperature sensor 46, a nylon baffle 47, and a shaft connecting block 48. The bearing protective cover 41 is embedded in the end opening of the tank body, and a rubber sealing sleeve 42 is fitted externally. The nylon baffle 47 presses the rubber sealing sleeve 42 between the bearing protective cover 41 and the inner wall of the tank body using countersunk screws, achieving a static seal. The connecting plate 43 is fixed to the outside of the bearing protective cover 41, and a self-aligning bearing with a mounting plate 45 is installed on it. The central support main pipe 3 is rotatably locked into the inner ring of the bearing. A PTFE-coated carbon fiber plug seal 44 is installed inside the bearing protective cover 41, clamping the outer wall of the main shaft to achieve a dynamic seal during rotation. The extended end of the central support main pipe 3 is fixed to the middle of the shaft connecting block 48 for meshing and transmission with the drive mechanism.

[0026] The central support main shaft 3 is a smooth, keyless optical shaft in the middle section. Its upper and lower ends are connected to the top self-aligning bearing 45 with a mounting seat and the bottom drive mechanism respectively via rotating shaft connecting blocks 48. A locking nut and a locking washer ensure axial bidirectional anti-loosening. The outer spherical surface of the self-aligning bearing 45 with a mounting seat can adaptively deflect within the bearing housing, automatically compensating for shaft deflection, installation eccentricity, and thermal expansion within a range of ±2°. This forms a multi-point self-aligning support assembly, ensuring that the main shaft, exceeding 4 meters in length, has a radial deviation of ≤0.3mm under full load of the double-layer spiral plate's self-weight and alternating gas-liquid load, completely eliminating the risk of the spiral plate rubbing against the tower wall. The temperature sensor 46 on the connecting plate 43 extends through the sealing component into the tank, forming a multi-point temperature monitoring network together with the temperature sensor 46 in the middle of the cylinder.

[0027] Please see Figure 1 and Figure 5 The low-speed rotary drive subsystem is located on the side of the bottom of the distillation tank body 1, and includes a double cross universal coupling 12, a reducer 13, an explosion-proof drive motor 14, and a water-cooling component 141. The explosion-proof drive motor 14 is arranged horizontally on the side, with its output end connected to the input end of the reducer 13. After reduction and torque amplification, the output end of the reducer 13 engages with the bottom rotating shaft connecting block 48 through the double cross universal coupling 12, achieving a 90° right-angle power transmission. The double cross universal coupling 12 can adaptively compensate for spindle deflection and installation eccentricity, ensuring smooth transmission without speed pulsation. The explosion-proof drive motor 14 is externally connected to an independent water-cooling component 141, isolating it from the high-temperature radiation of the tower bottom. The drive mechanism operates at a speed of 3-10 r / min, driving the central support main pipe 3 and all spiral mass transfer components 2 to rotate clockwise at a low speed synchronously, continuously disturbing the liquid film on the plate surface and generating a reverse cutting airflow to achieve self-cleaning of the sieve holes.

[0028] Please see Figure 1 and Figure 5The top demisting and condensation collection subsystem includes a gas phase perforation plate component 11, a demisting screen 15, a condenser 17, and a reflux tank 18. A top gas phase outlet 6 and a top gas phase reflux port 7 are respectively provided on both sides of the top of the distillation tank body 1. Gas phase perforation plate components 11 are fixedly installed inside the tank at positions corresponding to the two openings. The gas phase perforation plate component 11 includes a sealed shell 111 and a separation plate 112. Multiple evenly distributed separation holes 113 are opened on the separation plate 112. Its upper surface is treated with laser surface treatment to make it hydrophobic, preventing condensate droplets in the rising gas phase from adhering and allowing them to slide smoothly. The lower surface is sprayed with a hydrophilic coating, causing the dripping liquid phase to spread evenly and fall back to the spiral mass transfer component 2, achieving efficient gas-liquid separation.

[0029] A demister 15, made of 316L metal wire mesh, is installed on the top gas phase reflux port 7 to remove mist droplets and impurities entrained in the gas phase. A second shut-off valve 71 is installed on the external pipeline of the reflux port to control the on / off state of the circulation branch. The top gas phase outlet 6 is externally covered with an insulated pipeline 61 for full heat tracing, and a first shut-off valve 62 is installed on the outlet pipeline to control the on / off state of the high-temperature material being transported to the downstream tank. The top gas phase reflux port 7 is connected to the condenser 17 and the reflux tank 18 in sequence through pipelines. The condenser 17 completely condenses the rising gas phase into liquid, and the reflux tank 18 collects the condensed reflux liquid.

[0030] The circulating reboiling and operating condition switching subsystem is key to achieving multiple closed-loop boiling cycles and multi-stage high-temperature, non-cooling conveying. It includes a raw material preheater 19, a reboiler 22, a storage tank group 23, a filter 24, a pneumatic regulating valve 5, and a dual-path shut-off valve group. The output of the reflux tank 18 is connected to the input of the raw material preheater 19 via a pipeline. The output of the raw material preheater 19 is connected in series with a circulating pump. The pump output is connected to the bottom vapor inlet 8 of the column via the filter 24. A pneumatic regulating valve 5 is installed on the bottom vapor inlet 8 to precisely control the feed flow rate and pressure. The filter 24 has a built-in stainless steel sintered filter screen to remove polymers and crystalline particles from the circulating material. A reboiler 22 is also installed on the side wall of the distillation tank 1, located above the bottom vapor inlet 8. It can be heated by heat transfer oil or steam to reheat and vaporize the incoming material.

[0031] The input end of the raw material preheater 19 is also connected to the output end of the storage tank group 23 via a pipeline. The input end of the storage tank group 23 is connected to the insulated pipeline 61 of the previous stage unit, forming a high-temperature material receiving interface for the multi-stage distillation series system. The dual-mode switching is achieved through the linkage of the first shut-off valve 62 and the second shut-off valve 71: during the circulation purification stage, the second shut-off valve 71 is opened and the first shut-off valve 62 is closed, and the material circulates in a closed loop within the tank; after the purity reaches the standard, the second shut-off valve 71 is closed and the first shut-off valve 62 is opened, and the high-temperature material is directly sent to the next stage tank through the insulated pipeline 61, without intermediate transfer and cooling throughout the process, reducing the energy consumption of the multi-stage distillation system by 15%-22%.

[0032] The process monitoring subsystem includes a temperature sensor 46, an absolute pressure transmitter, and a differential pressure transmitter. The temperature sensor 46 is installed on the connecting plate 43 of the upper and lower sealing components 4 and in the middle of the cylinder, respectively, to monitor the temperature at the top, bottom, and middle of the column in real time. The absolute pressure transmitter is fixedly installed at the top of the inside of the distillation tank cylinder 1, monitoring the operating pressure at the top of the column with absolute vacuum as the zero point. This serves as the core basis for distillation pressure control and safety interlocking, and is particularly suitable for high-vacuum, low-temperature distillation conditions such as NMP. The positive pressure side of the differential pressure transmitter is connected to the gas phase space at the bottom of the cylinder, and the negative pressure side is connected to the gas phase space at the top of the cylinder, monitoring the pressure drop across the entire column in real time. This serves as a direct indicator for judging flooding, submersion, leakage, dry column, and sieve blockage. The absolute pressure transmitter and the differential pressure transmitter work together to ensure the pressure control accuracy and operational stability of the distillation process.

[0033] A distillation process employing a multi-channel spiral plate high-precision distillation apparatus includes the following steps: S1. Initial vaporization feed corresponds to the reboiling subsystem → mass transfer separation subsystem: The material to be separated is preheated in the raw material preheater 19 via the storage tank group 23 or external feed pipeline, then transported by the circulating pump, precisely filtered by the filter 24, and completely vaporized into a gas-liquid phase mixture in the reboiler 22; the gas-liquid phase material is introduced into the bottom of the cylinder through the gas phase inlet 8 at the bottom of the tower via the pneumatic regulating valve 5, and enters the spiral gas phase interlayer channel between the first spiral mass transfer inner element 20 and the second spiral mass transfer inner element 21 of the multiple sets of spiral mass transfer components 2, flowing from bottom to top along the spiral channel. The upward force of the gas phase assists in driving the spiral mass transfer component 2 to rotate, and the low-speed rotation drive subsystem provides a stable auxiliary driving force.

[0034] S2. The core working process of the reverse mass transfer separation subsystem: The rising steam in the spiral gas phase interlayer channel first penetrates the mass transfer sieve 204 of the second spiral mass transfer internal 21 and comes into reverse bubbling contact with the liquid film on its upper surface. The light component is transferred from the liquid phase to the gas phase, while the heavy component remains in the liquid phase. Subsequently, the gas phase continues to penetrate upward through the mass transfer sieve 204 of the first spiral mass transfer internal 20 and comes into reverse contact with the liquid film on its upper surface again, completing the secondary mass transfer. In terms of the liquid phase, a small amount of liquid phase falls vertically through the mass transfer sieve 204, while most of the liquid phase is forced to slowly descend layer by layer along the spiral slope through the connecting guide pipe 202, which greatly prolongs the gas-liquid contact time and mass transfer path. Finally, the heavy component slides down along the outer overflow weir 203 to the bottom of the cylinder and is periodically discharged through the waste liquid outlet 9 of the tower bottom. During this process, the single-board pressure drop is 50Pa-200Pa, the single-board Meurve efficiency is 60%-85%, and the theoretical equivalent board height is only 0.05m-0.15m, achieving efficient mass transfer under extremely low pressure drop.

[0035] S3, Tower Top Purification and Condensation Collection Subsystem: The gas phase carrying light components rises to the top of the cylinder and undergoes gas-liquid pre-separation via the separation plate 112 of the gas phase through-plate component 11. The upper surface is hydrophobically treated to allow droplets to slide off, while the lower surface is coated with a hydrophilic coating to ensure the liquid phase spreads evenly and falls back. Subsequently, the gas phase passes through the tower top gas phase reflux port 7 and passes through the demister 15 to remove mist and impurities. At this time, the second shut-off valve 71 opens and the first shut-off valve 62 closes. The gas phase enters the condenser 17 through the circulation pipeline and is completely condensed into liquid, which is then collected in the reflux tank 18.

[0036] S4. Closed-loop multiple-cycle purification corresponding to the closed-loop reboiling subsystem → mass transfer separation subsystem: The reflux liquid in the reflux tank 18 is pumped into the raw material preheater 19 for preheating. After being filtered by the filter 24, it first enters through the gas phase inlet 8. At this time, the reboiler 22 will successively enter the mixed gas phase that entered through the gas phase inlet 8, adjust the temperature, and then enter the tank again to complete the closed-loop mass transfer cycle, completing one round of closed-loop mass transfer. The material can be repeatedly circulated 3-8 times according to process requirements. Each cycle completes a complete vaporization-mass transfer-condensation-revaporization process, and the purity of the light components is gradually improved.

[0037] S5. High-Temperature, Non-Cooling Multi-Stage Conveying Subsystem for Switching Between Operating Conditions: After the material in this tank has circulated a specified number of times and reached the required purity, the second shut-off valve 71 is closed, and the first shut-off valve 62 is opened. The high-temperature gas phase is directly conveyed through the gas phase outlet 6 at the top of the tower and the insulated pipeline 61 to the liquid storage tank group 23 of the next-stage distillation tank body 1. After being heated and pressurized by the reboiler 22 of the lower-stage tank, it undergoes deep separation. The material remains at a high temperature throughout the process, with no intermediate cooling links and no need for repeated vaporization and heating.

[0038] S6. Continuous self-cleaning operation corresponding to the low-speed rotation drive subsystem + main shaft support subsystem: Throughout the distillation process, the explosion-proof drive motor 14 is reduced in speed and increased in torque by the reducer 13, and drives the central support main pipe 3 and all spiral mass transfer components 2 to rotate clockwise at a low speed of 3-10 r / min through the double cross universal coupling 12. On the one hand, the rotation continuously disturbs the liquid film on the plate surface, inhibiting crystal deposition and adhesion; on the other hand, the reverse cutting airflow generated by the spiral plate rotation continuously scours the mass transfer sieve holes 204, and with the smooth hole walls processed by laser, it is difficult for salt crystals and polymers to adhere and clog. At the same time, the multi-point self-aligning support assembly constrains the eccentric vibration of the long main shaft, with a radial offset of ≤0.3mm, ensuring that there is no scraping between the spiral plate and the tower wall, and the continuous operation cycle of the equipment is more than 3 times longer than that of traditional fixed packing plates.

[0039] S7. High-vacuum and low-temperature control of the process monitoring subsystem for NMP heat-sensitive material purification: When applied to the purification of highly heat-sensitive substances such as N-methylpyrrolidone (NMP), the preheated NMP waste liquid is fed into the upper part of the cylinder. The liquid spreads along the surfaces of the first spiral mass transfer inner element 20 and the second spiral mass transfer inner element 21 to form a uniform liquid film. The internal operating pressure of the cylinder is controlled at a high vacuum of 1kPa-10kPa by an absolute pressure transmitter, and the operating temperature at the bottom of the cylinder is controlled at 80℃-120℃ and the operating temperature at the top of the cylinder at 40℃-80℃ by a temperature sensor 46. The high vacuum significantly lowers the boiling point of NMP, effectively avoiding high-temperature thermal decomposition and polymerization; the extremely low single-plate pressure drop significantly reduces the overall pressure drop of the tower, and the reboiler does not need to maintain an excessively high temperature to provide mass transfer driving force, making it particularly suitable for high-precision purification of heat-sensitive materials.

[0040] Example 1: Large-scale industrial circulating distillation unit In this embodiment, the distillation tank body 1 has a diameter of 1000mm and a straight section height of 3000mm, and is welded from 316L stainless steel. The spiral mass transfer component 2 is made of 2mm thick 316L stainless steel plate, with a gas phase interlayer spacing of 20mm, a spiral helix angle of 12°, and an overflow weir 203 with a height of 20mm; the mass transfer sieve holes 204 have a diameter of φ4mm and a hole center distance of 14mm, and are opened with coaxial assistance from ultraviolet laser and high-purity nitrogen; the connecting guide pipe 202 has a diameter of φ10mm, and is arranged in sets every 2 turns. The central support main pipe 3 has an outer diameter of 89mm and is supported by a three-point self-aligning bearing 45 with a top seat, a bottom rotating shaft connecting block 48, and a double cross universal coupling 12. The explosion-proof drive motor 14 has a speed of 6r / min and is equipped with an independent water-cooling component 141. The vapor phase at the top of the column passes sequentially through a demister 15, a condenser 17, and a reflux tank 18. The reflux tank 18 is connected to a reboiler 22 heated by heat transfer oil. Secondary steam enters the column through the bottom vapor inlet 8. After the material is continuously circulated 5 times, the second shut-off valve 71 is automatically closed and the first shut-off valve 62 is opened. The high-temperature liquid is sent to the next stage tank through the insulated pipe 61. Application effect: Used for the purification of ethyl acetate-ethanol mixed solvent, the product purity is ≥99.95% after 5 cycles. The energy consumption of multi-stage processing is reduced by 16%. It can operate continuously and stably for 25 days without sieve blockage or shaft vibration deviation.

[0041] Example 2: Medium-sized pharmaceutical intermediate purification device In this embodiment, the distillation tank 1 has a diameter of 800mm and a straight section height of 3200mm. The spiral mass transfer component 2 is made of 2mm thick 316L stainless steel plate, with a gas phase interlayer spacing of 18mm, a spiral helix angle of 11°, and an overflow weir 203 with a height of 18mm; the mass transfer sieve 204 has a diameter of φ3.5mm and a center-to-center distance of 13mm; the connecting guide pipe 202 has a diameter of φ10mm, arranged in sets of 3 turns. The central support main pipe 3 has an outer diameter of 76mm, with top + bottom + double cross universal three-point self-aligning support. The explosion-proof drive motor 14 has a speed of 5r / min. The reboiler 22 is heated by steam. After 4 material circulations, the material is switched to the next stage tank. Application effect: Used for the purification of pharmaceutical intermediates, it runs continuously for 18 days without clogging, with a stable product purity of 99.92%, and the energy consumption of the multi-stage distillation system is reduced by 18%.

[0042] Example 3: Small-scale laboratory distillation apparatus In this embodiment, the distillation tank 1 has a diameter of 500mm and a height of 2200mm. The spiral mass transfer component 2 has a plate thickness of 1.5mm, a gas phase interlayer spacing of 15mm, and a mass transfer sieve with 204 holes and a diameter of φ3mm. The central support main pipe 3 is supported by self-aligning bearings 45 at both the top and bottom. The explosion-proof drive motor 14 has an adjustable speed of 3-8 r / min. A metal wire mesh demister 15 is installed at the top of the column, along with a small electric reboiler 22. After three material circulations, the high-temperature discharge is switched. This embodiment is suitable for intermittent high-precision distillation of low-viscosity pharmaceutical intermediates. The equipment has a small footprint, is easy to clean and maintain, and can achieve a laboratory purification purity of over 99.5%.

[0043] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. A multi-channel spiral plate high-precision distillation apparatus, comprising a distillation tank body (1), a central support main pipe (3), a low-speed rotation drive mechanism, a top defoaming and condensation collection unit, and a circulating reboiling unit, characterized in that: The upper and lower ends of the distillation tank body (1) are fixedly installed with sealing components (4), and the central support main pipe (3) is rotatably locked at the center position of the two sealing components (4). The sealing components (4) are used to achieve rotational sealing of the central support main pipe (3). Multiple sets of evenly distributed spiral mass transfer components (2) are fixedly installed on the central support main pipe (3). The spiral mass transfer component (2) includes a first spiral mass transfer inner element (20) and a second spiral mass transfer inner element (21). A spiral gas phase interlayer channel is formed between the first spiral mass transfer inner element (20) and the second spiral mass transfer inner element (21). A bottom gas phase inlet (8) is provided on one side of the bottom end of the distillation tank body (1). The bottom gas phase inlet (8) is connected to multiple gas phase interlayer channels.

2. The multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The first spiral mass transfer inner component (20) and the second spiral mass transfer inner component (21) are provided with a plurality of uniformly distributed guide grooves (201). The first spiral mass transfer inner component (20) and the second spiral mass transfer inner component (21) are also provided with a plurality of uniformly distributed mass transfer sieve holes (204). The mass transfer sieve holes (204) and the guide grooves (201) are staggered. The first spiral mass transfer inner component (20) and the second spiral mass transfer inner component (21) are each fixedly installed with a plurality of overflow weirs (203). The first spiral mass transfer inner component (20) and the second spiral mass transfer inner component (21) are fixedly connected with a plurality of sets of guide short pipes (202). The number of each set of guide short pipes (202) is set to a plurality. The guide short pipes (202) penetrate the first spiral mass transfer inner component (20) and the second spiral mass transfer inner component (21).

3. The multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The sealing component (4) includes a bearing guard (41), and a rubber sealing sleeve (42) is fitted over the bearing guard (41). The bearing guard (41) is embedded inside the distillation tank body (1). A connecting plate (43) is fixedly installed on the side of the bearing guard (41) away from the distillation tank body (1). A self-aligning bearing (45) with a seat is fixedly installed on the connecting plate (43). The central support tube (3) is rotatably locked in the middle of the self-aligning bearing (45). A nylon baffle (47) is provided below the rubber sealing sleeve (42). A rotating shaft connecting block (48) is provided below the nylon baffle (47). The central support tube (3) passes through the bearing guard (41) and the rubber sealing sleeve (42) and is then fixedly installed. In the middle of the rotating shaft connecting block (48), the nylon baffle (47) is fixedly installed on the bearing protective cover (41) by countersunk screws. The nylon baffle (47) tightly presses the rubber sealing sleeve (42) against the outside of the bearing protective cover (41). The bearing protective cover (41) is fixedly installed with a PTFE plus carbon fiber plug seal (44) to increase the sealing between the bearing protective cover (41) and the central support tube (3). A temperature sensor (46) is fixedly installed on the connecting plate (43). The temperature sensor (46) extends through the connecting plate (43), the rubber sealing sleeve (42), and the bearing protective cover (41) to the inside of the distillation tank body (1). A temperature sensor (46) is also fixedly installed in the middle of the distillation tank body (1).

4. The multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The low-speed rotary drive mechanism includes a double cross universal joint (12), a reducer (13), and an explosion-proof drive motor (14). One end of the double cross universal joint (12) is meshed with the output end of the reducer (13), and the end of the double cross universal joint (12) away from the reducer (13) is meshed with a rotating shaft connecting block (48). The input end of the reducer (13) is fixedly installed with the output end of the explosion-proof drive motor (14). The explosion-proof drive motor (14) is externally connected to a water-cooling component (141).

5. The multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The top of the distillation tank body (1) is provided with a top gas phase outlet (6) and a top gas phase reflux port (7) on both sides. Inside the distillation tank body (1), a gas phase pass-through plate component (11) is fixedly installed at the corresponding positions of the top gas phase outlet (6) and the top gas phase reflux port (7). The gas phase pass-through plate component (11) includes a sealing shell (111) and a separation plate (112). The separation plate (112) has multiple evenly distributed separation holes (113). The upper surface of the separation plate (112) is treated with a laser surface treatment process to make it hydrophobic. The lower surface of the separation plate (112) is sprayed with a hydrophilic coating.

6. The multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The external of the gas phase outlet (6) at the top of the tower is covered with an insulated pipe (61). A first shut-off valve (62) is fixedly installed on the gas phase outlet (6) at the top of the tower. A demister (15) is fixedly installed on the gas phase reflux port (7) at the top of the tower. A second shut-off valve (71) is also fixedly installed on the gas phase reflux port (7) at the top of the tower. A bottom waste liquid outlet (9) is provided on the side of the bottom of the distillation tank body (1) away from the bottom gas phase inlet (8). A solenoid valve is installed on the bottom waste liquid outlet (9). A pneumatic regulating valve (5) is installed on the bottom gas phase inlet (8).

7. A multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The circulating reboiler unit includes a condenser (17), a raw material preheater (19), a reboiler (22), a storage tank group (23), and a filter (24). The gas phase reflux port (7) at the top of the tower is connected to the input end of the condenser (17) through a pipe. The output end of the condenser (17) is connected to the input end of the reflux tank (18) through a pipe. The output end of the reflux tank (18) is connected to the input end of the raw material preheater (19) through a pipe. The output end of the raw material preheater (19) is connected in series with a pump body that drives the material circulation. The output end of the pump body is connected to the input end of the filter (24) through a pipe. The output end of the filter (24) is connected to the gas phase inlet (8) at the bottom of the tower through a pipe.

8. A multi-channel spiral plate high-precision distillation apparatus according to claim 7, characterized in that: The distillation tank body (1) is equipped with a reboiler (22) for heating circulating gas. The reboiler (22) is located above the bottom gas inlet (8). The input end of the raw material preheater (19) is also connected to the output end of the storage tank group (23) through a pipeline. The input end of the storage tank group (23) is fixedly connected to the insulation pipeline (61) of the adjacent unit above. The middle and lower part of the distillation tank body (1) is fixedly equipped with an inspection port (16).

9. A multi-channel spiral plate high-precision distillation apparatus according to claim 1, characterized in that: The pore size of the mass transfer sieve (204) is 2-3 mm. The mass transfer sieve (204) is in the shape of an equilateral triangle and is arranged in an array on the surface of the corresponding first spiral mass transfer inner element (20) and second spiral mass transfer inner element (21). The guide groove (201) does not penetrate the first spiral mass transfer inner element (20) or the second spiral mass transfer inner element (21). The guide groove (201) is only located on the upper surface of the first spiral mass transfer inner element (20) and the second spiral mass transfer inner element (21). An absolute pressure transmitter is fixedly installed at the top of the inside of the distillation tank body (1). A differential pressure transmitter is installed on the distillation tank body (1). The positive pressure side of the differential pressure transmitter is connected to the bottom end of the distillation tank body (1), and the negative pressure side of the differential pressure transmitter is connected to the top end of the distillation tank body (1).

10. A distillation process employing the multi-channel spiral plate high-precision distillation apparatus as described in any one of claims 1-9, characterized in that, Includes the following steps: S1, Initial vaporization feed: The material is completely vaporized into gas and liquid phases through the circulating reboiling unit, and is introduced into the spiral gas phase interlayer channel through the gas phase inlet (8) at the bottom of the tower, flowing from bottom to top along the spiral gas phase interlayer channel; S2, Reverse mass transfer separation: The vapor in the spiral gas phase interlayer channel penetrates the mass transfer sieve holes (204) on the first spiral mass transfer inner element (20) and the second spiral mass transfer inner element (21), and comes into contact with the liquid phase on the plate surface in reverse bubbling. The liquid phase is forced to flow downward along the spiral slope through the guide tube (202) connecting the first spiral mass transfer inner element (20) and the second spiral mass transfer inner element (21). S3, reflux purification and condensation: First close the first shut-off valve (61) and then open the second shut-off valve (71). At this time, the gas phase carrying light components rises to the top of the tower and passes through the top gas phase reflux port (7). After passing through the demister (15), the mist droplets are removed. Open the circulation pipeline valve and enter the condenser (17) for complete liquefaction. The liquefied reflux liquid is collected in the reflux tank (18). S4. Closed-loop multiple-cycle purification: The reflux liquid is sent into the circulating reboiling unit to boil and vaporize again. The high-temperature steam is reintroduced into the bottom gas phase inlet (8) to complete one cycle. Repeat the cycle 3-8 times to improve the purity of the material. After reaching the standard purity, close the second shut-off valve (71) and then open the first shut-off valve (61). At this time, the high-purity gas phase material will be transported to the next stage process through the heat-insulated pipe (61) for further purification. S5. High-temperature multi-stage conveying without cooling: After the material purity meets the standard, the second shut-off valve (71) is closed and the first shut-off valve (62) is opened. The high-temperature liquid reflux liquid is directly sent into the lower-level distillation tank body (1) for high-temperature boiling deep separation. S6. Continuous self-cleaning operation: The low-speed rotation drive mechanism continuously drives the spiral mass transfer component (2) to rotate at low speed, disturbing the liquid film on the plate surface to inhibit crystallization blockage; S7. After preheating, the NMP waste liquid is sent to the upper part of the distillation tank (1). Inside the distillation tank (1), the liquid spreads along the surface of multiple first spiral mass transfer internals (20) and second spiral mass transfer internals (21) to form a liquid film. The operating pressure inside the distillation tank (1) is controlled to be 1kPa-10kPa, the operating temperature at the bottom of the distillation tank (1) is 80℃-120℃, and the operating temperature at the top of the distillation tank (1) is 40℃-80℃. S8. The single-plate pressure drop of the first helical mass transfer internal component (20) and the second helical mass transfer internal component (21) is 50Pa-200Pa, the Meurveli efficiency of the single plate is 60%-85%, and the theoretical plate equivalent height is 0.05m-0.15m.

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