Apparatus for continuous dry heat distillation of an aromatic oil

Abstract

The application discloses a continuous dry heat distillation device for aromatic oil, and relates to the technical field of plant essential oil extraction equipment. The device comprises a horizontal cylindrical shell, a coaxial double-layer hollow screw shaft, a bidirectional gas supply and pulse control unit, a phase synchronization control system and a dust removal unit. The inner tube and the outer tube of the screw shaft form first and second gas path channels, respectively, and helical blades and concave scoops are alternately arranged on the shaft. The gas holes in the bottom of the concave surface of the scoop are connected to the low-pressure continuous gas path through a communication pipe, forming an air cushion to hold the material and a dynamic air curtain to block steam at the end gap. The radial gas holes on the outer tube corresponding to the two sides of the scoop are connected to the high-pressure pulse gas path. The high-pressure gas flow converges at the center of the concave surface to generate a gas surge, which makes the material puff and turn over, and strengthens the mass transfer. The device realizes low-loss and high-efficiency continuous distillation of the material through the cooperation of air cushion holding, air curtain steam blocking and pulse gas surge.

Description

Technical Field

[0001] This invention relates to the field of plant essential oil extraction equipment technology, specifically to a continuous dry hot distillation apparatus for aromatic oils. Background Technology

[0002] Aromatic oils are volatile aromatic components found in plants and are widely used in the food, daily chemical, and pharmaceutical industries. Currently, the industrial extraction of aromatic oils mainly uses steam distillation and dry heat distillation. Dry heat distillation does not use liquid water as a distillation medium; instead, it utilizes a heated gaseous medium to directly penetrate the material layer, evaporating and carrying away the essential oil, which is then condensed and recovered. Because the distillation temperature is not limited by the boiling point of water and no subsequent oil-water separation is required, dry heat distillation has potential advantages in terms of water conservation, energy efficiency, and essential oil quality.

[0003] Existing dry heat distillation equipment mostly adopts a horizontal rotary cylinder or screw conveyor structure; the material is axially conveyed within the cylinder by the cylinder's rotation or the screw blades, and is simultaneously heated and distilled by the heated cylinder wall or hot gas flow during the conveying process. Such equipment has revealed the following problems in practical applications: First, aromatic plant raw materials such as rose petals, materials, and lavender spikes are fragile after drying. They are easily damaged and broken by the mechanical pushing of the spiral blades, the tumbling and falling of the rotating cylinder, and the shearing action of the stirring plate. Mechanical damage not only produces a large amount of plant debris and dust, but also causes cell walls to rupture and release non-target components such as chlorophyll and tannins, giving the resulting essential oil a distinct grassy smell and bitter taste, which seriously reduces the quality.

[0004] Secondly, plant dust generated during distillation enters downstream condenser pipes, valves, and vacuum pumps along with the mixed steam, gradually depositing and forming a blockage layer. This not only reduces condensation efficiency but also forces frequent production interruptions for pipe cleaning, severely impacting continuous production capacity. Some units use filters or filter bags at the outlet to intercept dust, but the filter media is easily wetted and clogged by the essential oil condensate, requiring frequent replacement and resulting in a large maintenance workload.

[0005] Third, traditional equipment relies on mechanical stirring or cylinder rotation to agitate the material and bring it into contact with the hot gas flow. The more vigorous the stirring, the higher the mass transfer efficiency, but the more severe the material damage, creating a contradiction between "quality and efficiency." When the stirring intensity is reduced to minimize damage, the material becomes compacted, making it difficult for the hot gas flow to penetrate the material layer, resulting in a long and uneven distillation time.

[0006] Therefore, there is an urgent need for a continuous dry heat distillation device that can achieve flexible and damage-free material transport, efficient gas-solid mass transfer distillation, and effective dust interception throughout the entire distillation process. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an apparatus for continuous dry heat distillation of aromatic oils; The objective of this invention can be achieved through the following technical solutions: This application provides an apparatus for continuous dry heat distillation of aromatic oils, including... The shell is a horizontal cylindrical cavity with a feed inlet at the upper front end, a discharge outlet at the lower rear end, and a steam outlet at the top end. The inner wall has a jacket layer that extends axially and surrounds and covers the material contact section. The spiral shaft is horizontally and coaxially supported in the housing by a bearing seat and is driven to rotate by a motor. Its outer surface is provided with multiple spiral blades and multiple sets of lifting plates distributed along the axial direction. The spiral shaft is a hollow shaft with a coaxial double-layer structure, including an inner tube and an outer tube. The internal space of the inner tube forms a first air passage extending axially, and the passage between the inner tube and the outer tube forms a second air passage. The first air passage and the second air passage are independent of each other and are sealed and isolated from each other. The lifting plate is a concave lifting plate, the concave surface of which is in the shape of an arc groove, the end of which is close to the inner wall of the shell and there is a radial gap between it and the inner wall of the shell; multiple air holes are opened at the bottom of the concave surface of the lifting plate, and each air hole passes through the outer pipe wall, the first air passage (23) and the inner pipe wall in sequence through the connecting pipe embedded in the wall of the lifting plate, and finally connects to the second air passage. After passing through the outer pipe wall radially, it directly connects to the second air passage, and the connection between the connecting pipe and the outer pipe is sealed and welded. The connecting pipe does not enter the first air passage. The outer tube wall of the spiral shaft is also provided with multiple radial air outlets. The radial air outlets are distributed on the outer tube wall at corresponding positions on both sides of the concave surface of each lifting plate along the axial direction of the spiral shaft. The axis of each radial air outlet coincides with the line connecting the center point of the concave surface of the lifting plate to the intersection point of the outer tube wall where the air outlet is located in the radial plane containing the central axis of the spiral shaft, thus pointing to the central area of ​​the concave surface of the lifting plate. The radial air outlets are directly connected to the first air passage. The device further includes: a bidirectional gas supply and pulsation control unit, including a low-pressure continuous gas source connected to the second gas passage to provide low-pressure continuous gas, and a high-pressure pulsating gas source connected to the first gas passage to provide high-pressure pulsating gas, wherein a programmable valve is provided on the gas supply pipeline of the high-pressure pulsating gas source. The phase synchronization control system includes an encoder and a controller for real-time detection of the rotation angle of the helical shaft. The controller receives the encoder signal and controls the programmable valve to open when the helical shaft rotates to a preset trigger angle range, so as to generate periodic high-pressure air surge in the concave area of ​​the cutting plate. The dust removal unit is located above the steam outlet of the housing and is used to perform gas-solid separation on the discharged aromatic vapor.

[0008] Preferably, a dual-channel rotary joint is installed at the front end of the spiral shaft. The dual-channel rotary joint has a central interface and an annular interface. The central interface is connected to the second air passage, and the annular interface is connected to the first air passage, so that air can be supplied to the two channels independently when the spiral shaft is rotating.

[0009] Preferably, the low-pressure continuous gas source is a low-pressure fan with a continuous output pressure of 8 kPa. A gas preheater is installed on the outlet pipeline of the low-pressure fan, with a preheating temperature adjustment range of 60℃ to 200℃, so that the low-pressure gas entering the second gas path channel maintains a temperature that matches the distillation process. The high-pressure pulsating gas source includes a high-pressure gas storage tank with a storage pressure of 0.4 MPa. The programmable valve is a high-speed solenoid valve with a response time of less than 10 ms. An adjustable temperature gas heater is also installed on the pipeline between the high-pressure gas storage tank and the programmable valve, with a heating temperature adjustment range of 80℃ to 250℃.

[0010] Preferably, the controller is a programmable logic controller or a microcontroller, and the encoder is an absolute rotary encoder; the preset trigger angle range in the controller is from 0° to 45° of the azimuth angle of the copying board, and each copying board is triggered once for every rotation; the single opening duration of the programmable valve is 0.2 to 0.5 seconds.

[0011] Preferably, the concave depth of the lifting plate is 1 / 3 of the width of the lifting plate; the diameter of the air holes at the bottom of the concave surface is 2mm, which are evenly distributed along the axial direction of the lifting plate, and the spacing between adjacent air holes is 30mm; the ends of the lifting plate are rounded with a radius of 5mm; and the radial gap between the end of the lifting plate and the inner wall of the shell is 10mm.

[0012] Preferably, the jacket layer extends axially along the housing and surrounds and covers the material contact section inside the housing.

[0013] The beneficial effects of this invention are as follows: By coordinating the bottom air cushion support of the concave lifting plate with the axial propulsion of the spiral blade, the material is lifted off the metal surface in the lifting plate section and obtains stable thrust in the spiral blade section. This achieves flexible handling of the material without mechanical squeezing, forced friction, or throwing impact during the conveying process, eliminating the mechanical damage source that leads to the deterioration of essential oil quality from the perspective of damage mechanism.

[0014] By designing independent first and second air passages and separate air supply for low-pressure lifting air cushion and high-pressure pulsating air surge, the low-pressure air cushion continuously and stably lifts the material, while the high-pressure air surge briefly sprays the expanded material layer at a preset phase. The two do not interfere with each other, ensuring flexible lifting throughout the process and achieving efficient gas-solid mass transfer enhancement in the distillation section.

[0015] The phase synchronization control system controls the opening and closing of the programmable valve according to the rotation angle of the spiral shaft, so that the pulsating air surge is precisely triggered when the lifting plate rotates to the preset angle range. The action position and action time of the air surge are controllable, ensuring that the air surge penetrates the material layer in the best state where the material is constrained by the concave surface and the material layer is loose, avoiding the air surge from spraying and wasting gas or blowing away the material in non-effective areas.

[0016] By alternating the spiral blades and lifting plates in the axial direction, the material is axially propelled in the spiral blade section, and then lifted by air cushions and treated by pulsating air surges in the lifting plate section. This achieves an orderly alternation of propulsion and distillation in space, ensuring continuous and stable conveying while creating low-resistance, loose material layer conditions for air surge mass transfer.

[0017] By installing a cyclone separator at the steam outlet, centrifugal force is used to throw dust in the mixed steam toward the wall of the separator and slide down the wall to be discharged. This achieves dust interception without filter media and maintenance, protects the downstream condenser pipeline for long-term cleanliness, and ensures continuous production capacity. Attached Figure Description

[0018] To better understand and implement this application, the technical solution is described in detail below with reference to the accompanying drawings.

[0019] Figure 1 This is a structural diagram of an apparatus for continuous dry heat distillation of aromatic oils, as shown in Example 1. Figure 2 This is a structural diagram of the scraper plate of an apparatus for continuous dry heat distillation of aromatic oils, as shown in Example 1. Figure 3 This is a structural diagram of an apparatus for continuous dry heat distillation of aromatic oils provided in Example 3; 1-Shell; 11-Inlet; 12-Outlet; 13-Steam outlet; 14-Oil inlet; 15-Oil outlet; 2-Screw shaft; 21-Motor; 22-Second air passage; 23-First air passage; 24-Screw blade; 25-Lifting plate; 26-Radial air outlet; 31-Rotating cylinder; 32-Central shaft; 33-Drive motor; 34-Front end cover; 35-Rear end cover; 36-Electric heating unit; 37-Labyrinth seal; 38-Raw material inlet; 40-Gas outlet; 41-Slag outlet; 42-First heating section; 43-Second heating section; 44-Third heating section. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, exemplary embodiments will be described in detail below, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0021] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used herein are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0022] The following detailed description of the specific implementation methods, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided in detail.

[0023] Example 1 like Figure 1-2 As shown, the aromatic oil continuous dry heat distillation device provided in this embodiment includes a housing 1, a spiral shaft 2 coaxially arranged in the housing 1, a motor 21 for driving the spiral shaft 2 to rotate, and a dust removal unit arranged above the steam outlet 13 of the housing 1.

[0024] The housing 1 is a horizontal cylindrical cavity with an inner diameter of 500mm and an effective working length of 4000mm. The upper front end of the housing 1 is provided with a feed inlet 11, the lower rear end is provided with a discharge outlet 12, and the top end is provided with a steam outlet 13. A jacket layer is provided inside the wall of the housing 1, which extends along the axial direction of the housing 1 and surrounds and covers the entire material contact section. The bottom front end of the housing 1 is provided with an oil inlet 14, and the top rear end is provided with an oil outlet 15. Both the oil inlet 14 and the oil outlet 15 are connected to the jacket layer.

[0025] Furthermore, high-temperature heat transfer oil is continuously pumped into the jacket layer through the oil inlet 14, uniformly and indirectly heating the interior along the entire length of the shell before being discharged from the oil outlet 15 and circulated, maintaining the entire material contact section at a stable process temperature and providing a uniform thermal field for dry heat distillation; a rotary valve sealing mechanism is provided at both the feed inlet 11 and the discharge outlet 12, and the crushed aromatic plant raw materials are continuously and quantitatively added into the shell 1 through the rotary valve at the feed inlet 11. The rotary valve remains airtight during rotation to prevent the generated aromatic vapors from escaping; similarly, the solid residue after distillation is continuously discharged through the rotary valve at the discharge outlet 12 to ensure that the gas phase inside the shell does not leak during discharge; The spiral shaft 2 is horizontally supported within the housing 1 by bearing seats at both ends, with its axis coinciding with the axis of the housing 1. The spiral shaft 2 is a hollow shaft with a coaxial double-layer structure, including an inner tube and an outer tube. The internal space of the inner tube forms a first air passage 23 extending axially, and the passage between the inner and outer tubes forms a second air passage 22. The first air passage 23 and the second air passage 22 are independent of each other and are sealed and isolated from each other. A dual-channel rotary joint is installed at the front end of the spiral shaft 2. The dual-channel rotary joint has a central interface and an annular interface. The central interface is connected to the second air passage 22 through the connecting port at the front end of the inner tube, and the annular interface is connected to the first air passage 23 through a radial channel on the outer tube wall, thereby realizing independent air supply and rotation to the two channels respectively.

[0026] The motor 21 is a geared motor, and its output shaft is fixedly connected to the front end of the screw shaft 2 through a coupling; the motor 21 is driven by a frequency converter, and the speed of the screw shaft 2 can be steplessly adjusted within the range of 5-15 rpm.

[0027] Multiple helical blades 24 and multiple sets of lifting plates 25 are arranged axially on the outer surface of the helical shaft 2. The helical blades 24 and the lifting plate sets are arranged alternately in the axial direction, that is, a set of lifting plates is placed between every two adjacent helical blades 24. Each set of lifting plates consists of two lifting plates 25 arranged symmetrically at 180° along the circumference. Each helical blade 24 is detachably fixed to the helical shaft 2 by bolts, and its helical angle can be adjusted within the range of 15° to 45° to match the axial conveying speed of different materials.

[0028] Specifically, after the spiral shaft 2 is driven to rotate by the motor 21, the spiral blades 24 continuously push the material from the feed end to the discharge end. During the forward movement, the material is repeatedly scooped, lifted and scattered by each set of lifting plates 25. When the lifting plate 25 rotates to the bottom of the shell, the concave surface faces upward and scoops the material into the groove. As the shaft rotates, it is gradually lifted to a high position and then the material is scattered and falls by gravity, forming a thin layer of material curtain, which makes large-area contact with the hot wall surface and hot airflow. The aromatic oil components are heated and vaporized in this process.

[0029] The lifting plate 25 is a concave lifting plate, with its concave surface in the shape of an arc-shaped groove. The depth of the concave surface is 1 / 3 of the width of the lifting plate. The end of the lifting plate 25, i.e., the side near the inner wall of the shell 1, is rounded with a radius of 5mm. The radial gap between the end of the lifting plate 25 and the inner wall of the shell 1 is 10mm. Multiple air holes with a diameter of 2mm are opened at the bottom of the concave surface of the lifting plate 25. The air holes are evenly distributed along the axial direction of the lifting plate, with a spacing of 30mm between adjacent air holes. Each air hole passes radially through the outer pipe wall embedded in the lifting plate wall and directly connects to the second air passage 22. The connecting pipe does not pass through the first air passage 23 and finally connects to the second air passage 22. The penetration points of the connecting pipe with the outer and inner pipes are sealed by welding to ensure that the gas in the first air passage 23 will not leak into the second air passage 22 or the outside. All connecting pipes of the lifting plates 25 are connected to the second air passage 22 in the same way to achieve low-pressure continuous gas supply.

[0030] During operation, gas supplied by a low-pressure blower at a pressure of 8 kPa is preheated to the set temperature by a gas preheater and then enters the second gas passage 22 through the central interface of the dual-channel rotary joint. It then exits evenly through the air holes at the bottom of the concave surface of the lifting plate via connecting pipes 26. This low-pressure gas forms an air cushion between the concave surface and the material layer being lifted, lifting the material into a fluidized state, significantly reducing mass transfer resistance, preventing localized overheating of the material, and promoting the rapid migration of volatile components to the gas phase. Simultaneously, under the centrifugal force field introduced by the rotating screw shaft, some gas accelerates along the concave arc surface towards the end of the lifting plate, continuously ejecting from the 10mm gap between the end and the inner wall of the shell, forming a dynamically covering air curtain along the circumference. This air curtain is continuously refreshed and replenished by the rotation of the lifting plate, preventing aromatic vapors from escaping downwards through the gap and guiding the vapors to exit orderly through the steam outlet. It also continuously purges the gap to prevent small materials from embedding and provides a lifting effect on edge materials, helping them to fluff up and reducing mechanical damage.

[0031] Several radial air outlets 26 are also provided on the outer tube of the spiral shaft 2. These radial air outlets 26 are distributed on the outer tube wall surface corresponding to both sides of the concave surface of each lifting plate 25. The axis of the radial air outlets 26 is set in such a way that, in the radial plane including the central axis of the spiral shaft, the axis of each radial air outlet 26 coincides with the line connecting the intersection of the outer tube wall where the air outlet is located to the center point of the concave surface of the lifting plate, so that the ejected airflow is accurately directed to the central area of ​​the concave surface and directly connected to the first air passage 23. The axis of the radial air outlets 26 points to the central area of ​​the concave surface of the lifting plate. The high-pressure pulsed gas source is provided by a high-pressure gas storage tank with a gas storage pressure of 0.4 MPa. The gas is heated to a set temperature by an adjustable temperature gas heater, with an adjustment range of 80℃~250℃. After being determined according to the material type, it enters the first air passage 23 through the annular interface of the programmable valve and the dual-channel rotary joint. When the programmable valve is opened, high-pressure hot air is ejected at high speed from the radial air outlet 26 and converges in the central area of ​​the concave surface, forming a strong air surge effect. This causes the material to expand instantly, tumble violently, and generate turbulent mixing, which destroys the agglomeration structure and further enhances the mass transfer efficiency. At the same time, the converging airflow design avoids single-stream straight jets that would press the material onto the concave surface.

[0032] To achieve precise coordination between high-pressure pulsation and the position of the lifting plates, this device is equipped with a phase synchronization control system, including an absolute rotary encoder mounted on the output shaft of motor 21 and a PLC acting as the controller. The encoder zero-position calibration method is as follows: when the concave opening of any lifting plate is horizontal and facing upwards, that position is set to 0° for the encoder angle. The controller has a preset trigger angle range of 0° to 45° for the lifting plate azimuth angle, meaning the angle between the concave opening direction and the horizontal plane is within the range of 0° to 45°. When any lifting plate rotates into this range, the controller immediately sends an opening command to the programmable valve on the high-pressure gas line. The programmable valve opens for 0.2 to 0.5 seconds and then automatically closes. Thus, for each rotation of the spiral shaft 2, each lifting plate triggers a high-pressure pulsating gas surge, periodically enhancing the material agitation and evaporation in that area. Throughout the distillation process, the low-pressure continuous air cushion and air curtain continuously maintain basic fluidization and vapor barrier, while the high-pressure pulsating gas surge periodically intervenes to enhance mass transfer. The two work together to keep the material in an ideal distillation state with a loose texture and high exposure ratio.

[0033] The generated aromatic mixed steam, carrying a small amount of dust, is discharged from the steam outlet 13 at the top of the shell and enters the dust removal unit. The dust removal unit is a cyclone separator, located at the steam outlet 13 of the shell 1. It adopts a conventional tangential flow structure, consisting of an upper cylindrical section and a lower conical section. The air inlet is a rectangular tangential inlet, airtightly connected to the steam outlet 13 via a flange. After the dust-laden steam enters tangentially, the dust is thrown against the wall and falls to the bottom of the conical section under centrifugal force. Clean steam is led out from the top central exhaust pipe and sent to the downstream condensation and separation unit to recover the aromatic essential oils. The bottom dust outlet of the cyclone separator is connected to a detachable dust collection tank and a discharge valve. The discharge valve is a manual ball valve or an automatic discharge valve, which can be opened periodically during production to discharge the collected dust without stopping the machine or compromising the system's airtightness.

[0034] The solid residue after distillation is continuously pushed to the discharge port 12 by the spiral blades 24, and continuously discharged through the rotary valve sealing mechanism while keeping the gas phase inside the shell closed. This realizes continuous production from feeding, indirect dry heat distillation, air cushion and gas surge to enhance mass transfer, steam dust removal to discharge.

[0035] Example 2 This embodiment discloses an inert gas closed-loop circulating continuous dry-heat distillation apparatus for aromatic oils, used for the industrial extraction of high-value aromatic oils such as luxury-grade rose essential oil and jasmine essential oil, which are extremely sensitive to oxygen. This embodiment shares the same basic structure and working principle as Embodiment 1, with the main difference being: replacing air with inert gas as the working fluid for the high-pressure pulsed gas surge, and adding an inert gas circulation loop at the condensation and recovery end to achieve closed-loop recycling of the inert gas, further realizing a comprehensive performance leap in anaerobic distillation, enhanced self-organized mass transfer, pulsed self-cooling protection, and intrinsically safe zero emissions. Details are as follows: Unlike Example 1, which uses compressed air as a high-pressure pulsating gas source, this example uses food-grade nitrogen as the gas-suppressing working fluid in the high-pressure gas storage tank. Nitrogen is chemically inert within the distillation temperature range and does not react with aromatic oil components. Furthermore, its Joule-Thomson coefficient is positive above 150°C, resulting in a slight temperature drop during throttling, which provides a thermodynamic basis for the subsequent self-cooling protection effect.

[0036] The inert gas circulation and recovery system includes: an inert gas circulation loop added at the exhaust end of the condensation and separation device after the cyclone dust collector, which includes, in sequence along the airflow direction: Demister: Captures trace droplets carried in the condensed airflow to prevent liquid essential oils from entering the circulation system; Dryer: Adsorbs residual moisture in the airflow to ensure that the dew point of the circulating inert gas is below -40°C; Precision filters: remove any submicron-sized particles that may be present; Circulating compressor: pressurizes the low-pressure recovered inert gas to 0.15–0.2 MPa; Buffer tank: Stabilizes pressure fluctuations in the circulating airflow; Temperature controller: After the circulating gas is pre-adjusted to the set temperature, it is sent to the gas replenishment port of the high-pressure gas storage tank.

[0037] The booster compressor further pressurizes the 0.15-0.2 MPa gas at the outlet of the buffer tank to a level higher than the current pressure of the high-pressure gas storage tank, and then sends it into the gas supply port of the high-pressure gas storage tank through the automatic gas supply valve. The high-pressure gas storage tank is equipped with an automatic gas replenishment valve and a pressure sensor. When the pressure inside the tank drops below 0.39 MPa due to a slight leak, the gas replenishment valve at the outlet of the second-stage booster compressor is automatically opened to replenish fresh or recycled nitrogen, maintaining the system pressure at 0.4 ± 0.01 MPa. The entire circulation loop allows the inert gas to operate in a closed loop within the distillation system, without being discharged into the atmosphere.

[0038] During operation, high-pressure pulsating inert gas enters the first gas path channel 23 via a programmable valve and a dual-channel rotary joint. Within the trigger range of 0° to 45° azimuth angle of the lifting plate, it is ejected at high speed from the radial outlet 27, converging at the center of the concave surface to form a gas surge. Under the action of the gas surge, the material expands instantaneously, generating numerous micropores and fissures inside. Simultaneously, high-pressure inert gas molecules permeate into these newly formed microporous structures along with the gas surge. When the pulsation ends and the material rebounds and contracts, some of the inert gas is physically sealed within the micropores, forming countless tiny inert protective atmosphere cavities. These microcavities continuously protect the newly exposed active sites inside the material during subsequent distillation, preventing trace oxygen molecules that may exist in the shell from contacting the heat-sensitive aromatic components, thus significantly improving the retention rate of easily oxidized components such as unsaturated terpenes and aldehydes. This effect relies on the unique high-pressure pulsation and material expansion synchronization mechanism of this device, which cannot be achieved by atmospheric pressure inert gas flow protection or static inert atmosphere distillation.

[0039] Because the inert gas repeatedly travels between the high-temperature distillation zone and the low-temperature condensation zone in the closed-loop cycle, after the first cycle, the gas will contain trace amounts of low-boiling-point aromatic components. When these "fragrant" inert gases are heated again and injected into the material layer at high speed, the trace aromatic molecules carried in the gas flow act as "nuclei," promoting the diffusion and aggregation of similar molecules in the material towards them, forming a molecularly imprinted accelerated mass transfer effect. After multiple cycles, a dynamic equilibrium is established between the chemical potential of the inert gas and the distillation mixture. The distillation efficiency no longer depends solely on the temperature gradient but also gains an additional driving force guided by the concentration field, resulting in an increased extraction rate and a shortened distillation time. This self-organized enhanced mass transfer phenomenon cannot occur in open systems or single-pass gas flows and is unique to the closed-loop architecture of this embodiment.

[0040] When high-pressure inert gas is instantaneously released into the concave area of ​​the lifting plate at atmospheric pressure through a programmable valve, a tiny instantaneous temperature drop of 0.2–0.5°C occurs during the throttling process because nitrogen has a positive Joule-Thomson coefficient at temperatures above 150°C. Although this temperature drop is small, it occurs precisely at the moment when the material is most fully exposed to the gas surge and heat-sensitive components, making it most susceptible to overheating. This forms a peak thermal protection mechanism, preventing localized thermal decomposition of aromatic components. During the intermittent periods of the pulsation, the jacketed heat transfer oil maintains the basic distillation temperature. This paradoxical unity of "pulsating self-cooling and constant-temperature heating" allows this device to safely process high-value, delicate raw materials that previously required low-temperature vacuum distillation for protection, while simultaneously increasing the distillation rate, breaking the traditional inverse relationship between temperature and quality in distillation.

[0041] The fully inert closed-loop circulation makes the distillation system a closed unit that "only takes in materials and outputs essential oils and residues, without emitting any process gases into the atmosphere." On the one hand, it achieves zero emissions of volatile organic compounds; on the other hand, in the high-temperature environment of dry heat distillation, the inert atmosphere reduces the oxygen content in the system to the ppm level, completely eliminating the risk of dust explosions and organic vapor combustion explosions, thus achieving intrinsic safety.

[0042] The dimensions and structure of the housing 1, the coaxial double-layer structure and sealing method of the spiral shaft 2, the arrangement of the lifting plate 25 and the spiral blade 24, the welding and sealing of the connecting pipe 26, the arrangement of the radial air outlet 27, the low-pressure continuous air supply method, the frequency conversion drive of the motor 21, the encoder and PLC control logic of the phase synchronization control system, the structure and dust removal method of the dust removal unit, and the overall continuous production process of the device are all the same as those in Embodiment 1.

[0043] Example 3 like Figure 3 As shown, this embodiment provides a continuous dry heat distillation apparatus for aromatic oils, suitable for the continuous dry heat distillation of fresh flowers that are extremely small, have high water content, and are extremely sensitive to mechanical and thermal damage. The apparatus includes a rotating cylinder 31, a central shaft 32 coaxially arranged inside the rotating cylinder 31, a drive motor 33 for driving the rotating cylinder 31 to rotate, an electric heating unit wound around the outer wall of the rotating cylinder 31, a feeding and dispersing device arranged above the feeding end of the rotating cylinder 31, and a dust removal unit arranged at the gas outlet 40.

[0044] The rotating cylinder 31 is a horizontal cylindrical structure with an inner diameter of 400mm and a length of 3000mm, made of 304 stainless steel. The inner wall of the rotating cylinder 31 is polished to a surface roughness Ra of 0.4μm and coated with Teflon. Spiral blades are axially arranged on the inner wall of the rotating cylinder 31, rotating with the cylinder to propel the material towards the discharge end. The spiral blades have a lead of 300mm, a blade height of 20mm, a blade thickness of 3mm, and rotate clockwise. They are continuously welded to the inner wall of the rotating cylinder 31. The cylindrical section of the rotating cylinder 31 is supported by two sets of front and rear support rollers, and the entire machine is tilted towards the discharge end at an angle of 1.5°. The rotating cylinder 31 has a front cover 34 at the front end and a rear cover 35 at the rear end. Both the front cover 34 and the rear cover 35 are fixed to the frame, and the cylindrical section of the rotating cylinder 31 rotates between them.

[0045] Furthermore, a labyrinth seal 37 is provided in the annular gap between the rotating cylinder 31 and the front end cover 34 and the rear end cover 35. The labyrinth seal 37 is composed of multiple annular teeth and annular grooves alternatingly. The annular teeth and annular grooves are respectively set on the outer circular surface of the end of the rotating cylinder 31 and the inner surface of the corresponding front end cover 34 and rear end cover 35. A tortuous gap is formed between the teeth and the grooves. The gap is filled with high-temperature resistant grease. With the help of the centrifugal force generated during rotation and the viscous resistance of the grease, relative rotational movement is allowed while maintaining airtightness.

[0046] Furthermore, the upper part of the front cover 34 is provided with a raw material inlet 38, and the upper part of the rear cover 35 is provided with a gas outlet 40. The gas outlet 40 is directly connected to the interior of the rotating cylinder 31 and is located in the area above the central axis of the rotating cylinder 31, used to export the mixed steam generated by distillation. The lower part of the rear end of the cylindrical section of the rotating cylinder 31 is provided with a slag outlet 41, and a rotary valve is provided at the slag outlet 41.

[0047] The drive motor 33 is a variable frequency geared motor, which drives the rotating cylinder 31 to rotate through a gear transmission mechanism. The gear transmission mechanism includes a driving gear mounted on the output shaft of the drive motor 33 and a driven gear ring mounted on the outer wall of the rotating cylinder 31. During operation, when the drive motor 33 is started, the rotating cylinder 31 rotates at a speed of 5 rpm, and the speed can be steplessly adjusted within the range of 3-10 rpm. The Teflon coating on the inner wall of the rotating cylinder 31 reduces the coefficient of friction between the material and the wall surface, which, together with the pushing action of the spiral blades and the air film described later, achieves low-damage material conveying.

[0048] The central shaft 32 has a double-layered sleeve structure and is horizontally arranged along the axis of the rotating cylinder 31. The front end of the central shaft 32 is fixed to the center of the front end cover 34, and the rear end is fixed to the center of the rear end cover 35, and does not rotate with the rotating cylinder 31. The central shaft 32 has independent low-pressure gas channels and high-pressure gas channels inside. The front end of the low-pressure gas channel has a low-pressure gas inlet, which extends through the front end cover 34 and is connected to a low-pressure preheating gas source via a rotary joint. The front end of the high-pressure gas channel has a high-pressure gas inlet, which extends through the front end cover 34 and is connected to a high-pressure pulsating gas source via another rotary joint.

[0049] Furthermore, low-pressure jet holes and high-pressure jet holes are formed on the outer tube wall of the central shaft 32. The low-pressure jet holes are connected to the low-pressure gas channel, arranged along a spiral line with a pitch of 60 mm, 10 holes per circle, and a hole diameter of 1.5 mm. Their gas outlet direction is radially perpendicular to the inner wall of the rotating cylinder 31, used to form a lifting gas film between the material and the cylinder wall, isolating the material from the cylinder wall. The high-pressure jet holes are connected to the high-pressure gas channel and are set on the outer tube wall corresponding to the main distillation section of the material. The high-pressure jet holes have a hole diameter of 2 mm, an axial spacing of 100 mm, and 6 holes are evenly distributed per circumferential circle, distributed within a length range of 1.0 m to 2.4 m in the middle section of the rotating cylinder 31. They are staggered with the low-pressure jet holes in the axial and circumferential directions, and the gas outlet direction is radially outward.

[0050] During operation, the centrifugal fan and electric preheater are started. Preheated air at 95℃ continuously enters the low-pressure gas channel from the low-pressure gas inlet at a pressure of 8 kPa, and is ejected through the low-pressure jet nozzle. The radial air output from the low-pressure jet nozzle forms a lifting gas film near the inner wall of the rotating cylinder 31, isolating the material from the cylinder wall and eliminating hard contact friction between the material and the cylinder wall. Simultaneously, the high-pressure pulsed gas source is activated. High-pressure gas at 0.3-0.5 MPa in the high-pressure storage tank periodically enters the high-pressure gas channel from the high-pressure gas inlet through the programmable valve, and is ejected through the high-pressure jet nozzle in short, pulsating bursts. The programmable valve is electrically connected to the phase synchronization control system and briefly opens when the rotating cylinder 31 rotates to the preset phase. The pulse frequency is twice per revolution, meaning the programmable valve opens twice for every revolution of the rotating cylinder 31; each pulse lasts for 0.3 seconds, and the gas flow rate for a single pulse is 0.05 m³ / s. 3 The duty cycle is 1:10.

[0051] The electric heating unit is a silicone rubber electric heating strip, 80mm wide, with a power density of 0.6W / cm³. 2The electric heating unit is wound around the outer wall of the rotating cylinder 31 and is divided into three independently controlled sections along the axial direction: the first heating section 42 is located in the feeding section, with a length of 0.8m and a total power of 8kW; the second heating section 43 is located in the middle section, with a length of 1.4m and a total power of 12kW; and the third heating section 44 is located in the discharging section, with a length of 0.8m and a total power of 8kW. Each heating section is connected to a slip ring via wires. The slip ring is a 6-channel carbon brush slip ring, with a rated current of 20A and a rated voltage of 380V per channel, and is installed at the front end of the rotating cylinder 31. The temperature control system includes three independent PID controllers, three solid-state relays, and three temperature sensors. The three temperature sensors are all K-type thermocouples, installed close to the outer wall of the rotating cylinder 31, located at the center of the first heating section 42, the second heating section 43, and the third heating section 44. Each PID controller independently controls the on / off state of each heating section through the corresponding solid-state relay based on the temperature signal detected by the corresponding temperature sensor. The electric heating unit is covered with an insulation layer, which is an aluminum silicate fiber blanket with a thickness of 80mm, and is covered with a stainless steel protective skin.

[0052] During operation, the temperature control system is activated, setting the temperature of the first heating section 42 to 100℃, the second heating section 43 to 130℃, and the third heating section 44 to 140℃. After each section reaches its set temperature and stabilizes, the inner wall temperature of the shell corresponding to the first heating section 42 during steady-state operation is 99–101℃, the second heating section 43 is 129–131℃, and the third heating section 44 is 139–141℃. The gas phase pressure inside the rotating cylinder 31 is maintained at a slightly positive pressure of approximately 1 kPa.

[0053] This device also includes a feeding and dispersing device, which adopts a reverse-facing double-belt structure and is located above the raw material inlet. It is used to gently break up the osmanthus flowers that are naturally clumped together due to their high moisture content into individual flowers before they enter the rotating cylinder, so as to avoid uneven heating inside the cylinder after they are clumped together.

[0054] The feeding and dispersing device comprises two identical belt units, symmetrically arranged in a vertical plane. Each belt unit includes a driving shaft, a driven shaft, and a ring belt. The belt unit on the left includes a first driving shaft, a first driven shaft, and a first ring belt; the belt unit on the right includes a second driving shaft, a second driven shaft, and a second ring belt. The first and second driving shafts are at the same horizontal level and are independently driven by a first speed-regulating motor and a second speed-regulating motor, respectively. The first and second driven shafts are also at the same horizontal level. The center distance between the first and second driving shafts is greater than the center distance between the first and second driven shafts, creating a vertical material channel that gradually narrows from top to bottom between the inner working surfaces of the first and second ring belts.

[0055] The inner working surfaces of the first and second annular belts face each other, and both surfaces are pressed with a diamond-shaped mesh pattern with a pattern height of 1.5 mm. The minimum gap between the surfaces of the first and second driven shafts is 5 mm, which is slightly larger than the average size of a single osmanthus flower, allowing individual flowers to pass through smoothly while applying a gentle rubbing force to clusters of flowers.

[0056] During operation, the first and second speed-regulating motors drive the first and second drive shafts to rotate in opposite directions, causing the inner working surfaces of both the first and second annular belts to move downwards at a speed of 0.8 m / s. Fresh osmanthus flowers are fed into the material channel from above and are simultaneously clamped and conveyed downwards by the two belts. As the channel gradually narrows from top to bottom, the diamond-shaped mesh on the belt surface applies uneven friction to the flower clusters, gently breaking them apart into individual flowers as they move downwards. The broken-up individual flowers are discharged through the 5mm gap between the first and second driven shafts and fall into the rotating cylinder through the raw material inlet 38.

[0057] After the material enters the rotating cylinder 31, the cylinder rotates at 5 rpm. The spiral blades on the inner wall propel the material towards the discharge end. Simultaneously, the Teflon coating on the inner wall and the gas film formed by the preheated gas ejected from the low-pressure jet holes work together to lift the material and suspend it near the cylinder wall, preventing direct hard compression against the metal surface. The spiral blades rotate with the rotating cylinder 31, applying an axial thrust towards the discharge end to the material. The gravitational component generated by the 1.5° tilt angle of the entire machine assists the material in sliding towards the discharge end. The low-pressure jet holes do not provide axial propulsion; they only provide radial gas film support, isolating the material from the inner wall of the rotating cylinder 31 to avoid mechanical compression and friction damage. In the mid-distillation zone, the high-pressure jet holes periodically eject short bursts of high-pressure gas, causing the suspended material layer to expand and tumble instantaneously, enhancing gas-solid mass transfer and accelerating the volatilization of aromatic oils.

[0058] The material passes through three temperature zones sequentially within the rotating cylinder 31: in the feeding section, the material rapidly heats from room temperature to approximately 40–50°C; in the middle section, the material temperature rises to 65–75°C, where the main components of the aromatic oil volatilize in large quantities under the synergistic effect of low-pressure gas film support, gentle propulsion by the spiral blades, and high-pressure gas surge expansion; the discharge section ensures complete evaporation of residual aromatic oil. Throughout the process, the material is isolated from the cylinder wall by a gas film, without violent mechanical compression, and the residence time is approximately 50 minutes. The distilled material retains its complete flower shape, its color changes from bright yellow to light yellow, and the petal integrity rate is greater than 99%, before being discharged from the slag outlet 41 via a rotary valve.

[0059] The aromatic mixed vapors produced by distillation flow from the feed end to the discharge end within the rotating cylinder 31, and are discharged directly from the gas outlet 40 at the top of the rear cover 35, entering the cyclone separator. The gas outlet 40 is directly connected to the interior of the rotating cylinder 31, without needing to be discharged through the central shaft.

[0060] The system also includes a dust removal unit at the gas outlet 40, which is a cyclone separator with a cylinder diameter of 200 mm. The inlet of the cyclone separator is directly connected to the gas outlet 40 above the rear end cover 35 via a flange. A dust collection device is installed at the bottom dust outlet of the cyclone separator, comprising a dust collection tank and a discharge valve installed on a pipeline above the dust collection tank. The top exhaust pipe of the cyclone separator is connected to the downstream condensation and collection system. After the mixed steam enters the cyclone separator, under centrifugal force, trace amounts of dust are thrown against the wall and slide down the wall, falling into the bottom dust collection tank, which can be periodically discharged through the discharge valve. Clean steam is discharged from the top of the cyclone separator and enters the downstream condensation and collection system, where it is cooled and separated into oil and water to obtain refined oil.

[0061] This embodiment has the following beneficial effects: The structure, which uses the spiral blades on the inner wall of the rotating cylinder and the lifting air film ejected from the low-pressure jet hole on the central shaft, separates the axial mechanical propulsion of the material from the radial air film isolation function, so as to achieve stable material conveying in the cylinder without hard squeezing and friction with the cylinder wall throughout the process.

[0062] Through the independent low-pressure gas channel and high-pressure gas channel inside the central shaft, and the separate arrangement of low-pressure jet holes and high-pressure jet holes, the continuous lifting of the low-pressure gas film and the intermittent expansion of the high-pressure pulsating gas surge do not interfere with each other, so that the material is always suspended above the gas film, while receiving periodic gas surges to enhance mass transfer in the distillation section.

[0063] The electric heating unit is divided into three independent temperature control sections along the cylinder axis. Each section is equipped with an independent PID controller and solid-state relay. The temperature of the feeding section, the middle section and the discharging section can be precisely and independently adjusted to achieve gradient precise temperature control: 100℃ in the feeding section to prevent scalding, 130℃ in the middle section for efficient distillation, and 140℃ in the discharging section to ensure complete evaporation.

[0064] By using a reverse-direction dual-belt feeding and dispersing device, the inner sides of the two belts run downwards in the same direction, and the channel gradually narrows from top to bottom, a gentle and uneven frictional force is applied to the clump of material to disperse it, thereby breaking the material clump into individual flower-like states with no broken petals and uniform heating during distillation.

[0065] The resulting material has a pure and complete essential oil aroma, no off-odors from thermal degradation, and a petal integrity rate of over 99%.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A continuous dry heating distillation apparatus for aromatic oils, characterized in that ,include: The shell (1) is a horizontal cylindrical cavity with an inlet (11) at the upper front end, an outlet (12) at the lower rear end, and a steam outlet (13) at the top end. The inner wall is provided with a jacket layer that extends axially and surrounds the material contact section. The spiral shaft (2) is horizontally and coaxially supported in the housing (1) by a bearing seat and driven to rotate by a motor (21). Its outer surface is provided with multiple spiral blades (24) and multiple sets of lifting plates (25) distributed along the axial direction. The spiral shaft (2) is a hollow shaft with a coaxial double-layer structure, including an inner tube and an outer tube. The internal space of the inner tube forms a first air passage (23) extending along the axial direction. The passage between the inner tube and the outer tube forms a second air passage (22). The first air passage (23) and the second air passage (22) are independent of each other and are sealed and isolated from each other. The lifting plate (25) is a concave lifting plate, and its concave surface is in the shape of an arc groove. Its end is close to the inner wall of the shell (1) and there is a radial gap between it and the inner wall of the shell (1). Multiple air holes are opened at the bottom of the concave surface of the lifting plate (25). Each air hole passes through the outer pipe wall, the first air passage (23) and the inner pipe wall in sequence through the connecting pipe embedded in the wall of the lifting plate, and finally connects to the second air passage (22). After passing through the outer pipe wall radially, it directly connects to the second air passage (22). The connection pipe and the outer pipe are sealed and welded at the penetration point. The connecting pipe does not enter the first air passage (23). The outer tube wall of the spiral shaft (2) is also provided with a plurality of radial air outlets (26). These radial air outlets (26) are distributed on the outer tube wall at corresponding positions on both sides of the concave surface of each lifting plate (25) along the spiral shaft axis. The axis of each radial air outlet (26) coincides with the line connecting the center point of the concave surface of the lifting plate to the point on the outer tube wall where the air outlet is located in the radial plane containing the central axis of the spiral shaft, thus pointing to the central area of ​​the concave surface of the lifting plate. The radial air outlets (26) are directly connected to the first air passage (23). The device further includes: a bidirectional gas supply and pulsation control unit, including a low-pressure continuous gas source connected to the second gas passage (22) to provide low-pressure continuous gas, and a high-pressure pulsating gas source connected to the first gas passage (23) to provide high-pressure pulsating gas, wherein a programmable valve is provided on the gas supply pipeline of the high-pressure pulsating gas source. The phase synchronization control system includes an encoder and a controller for real-time detection of the rotation angle of the helical shaft (2). The controller receives the encoder signal and controls the programmable valve to open when the helical shaft (2) rotates to a preset trigger angle range, so as to generate periodic high-pressure air surge in the concave area of ​​the cutting plate (25). The dust removal unit is located above the steam outlet (13) of the housing (1) and is used to perform gas-solid separation on the discharged aromatic steam.

2. The continuous dry hot distillation apparatus for aromatic oils according to claim 1, characterized in that: A dual-channel rotary joint is installed at the front end of the spiral shaft (2). The dual-channel rotary joint has a central interface and an annular interface. The central interface is connected to the second air passage (22), and the annular interface is connected to the first air passage (23), so that air is supplied to the two channels independently when the spiral shaft is rotating.

3. The continuous dry hot distillation apparatus for aromatic oils according to claim 1, characterized in that: The low-pressure continuous gas source is a low-pressure fan with a continuous output pressure of 8 kPa. A gas preheater is provided on the outlet pipe of the low-pressure fan, with a preheating temperature adjustment range of 60℃~200℃, so that the low-pressure gas entering the second gas passage (22) maintains a temperature that matches the distillation process. The high-pressure pulsating gas source includes a high-pressure gas storage tank with a storage pressure of 0.4 MPa. The programmable valve is a high-speed solenoid valve with a response time of less than 10 ms. An adjustable temperature gas heater is also provided on the pipeline between the high-pressure gas storage tank and the programmable valve, with a heating temperature adjustment range of 80℃~250℃.

4. The continuous dry hot distillation apparatus for aromatic oils according to claim 1, characterized in that: The controller is a programmable logic controller or a microcontroller, and the encoder is an absolute rotary encoder. The preset trigger angle range in the controller is from 0° to 45° of the azimuth angle of the copying board, and each copying board is triggered once for every rotation. The single opening time of the programmable valve is 0.2 to 0.5 seconds.

5. The continuous dry hot distillation apparatus for aromatic oils according to claim 1, characterized in that: The concave depth of the lifting plate (25) is 1 / 3 of the width of the lifting plate; the diameter of the air holes at the bottom of the concave surface is 2mm, which are evenly distributed along the axial direction of the lifting plate, and the distance between adjacent air holes is 30mm; the end of the lifting plate (25) is rounded with a radius of 5mm; the radial gap between the end of the lifting plate (25) and the inner wall of the shell (1) is 10mm.

6. The continuous dry hot distillation apparatus for aromatic oils according to claim 1, characterized in that: The jacket layer extends axially along the housing (1) and surrounds and covers the material contact section inside the housing (1).

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