A device and process for extracting citrus essential oil using supercritical CO2

Abstract

The present invention discloses a device for extracting citrus essential oils using supercritical CO2, which belongs to the technical field of extracting citrus essential oils. The device comprises an extraction tank containing citrus peels to be extracted, a bracket frame for mounting the extraction tank provided on the periphery of the extraction tank, an output shaft of a stirring motor extending into the extraction tank and fixed with a stirring shaft, a plurality of stirring and crushing blades symmetrically provided on the periphery of the upper portion of the stirring shaft, a grinding lower platen provided on the lower portion of the stirring shaft and located at the lower portion of the inner cavity of the extraction tank for lifting and lowering, at least two rectangular through-grooves symmetrically provided inside the grinding lower platen, a rectangular lifting block provided in each of the rectangular through-grooves for lifting and lowering, a crushing cutter member provided on the bottom surface of the rectangular lifting block for crushing and cutting the citrus peels to be extracted. The double crushing method of the present invention greatly improves the degree of crushing of the citrus peels and increases the effective contact area between the supercritical CO2 solvent and the citrus peels, thereby significantly improving the extraction efficiency and quality of the essential oils.

Description

Technical Field

[0001] The invention belongs to the technical field of extracting citrus essential oil, in particular to a device and a process for extracting citrus essential oil by supercritical CO2. Background Art

[0002] Supercritical CO2 extraction is a widely used method for extracting natural products, particularly suitable for heat-sensitive substances such as citrus essential oils. Traditional supercritical CO2 extraction equipment typically consists of a sealed extraction tank, where supercritical carbon dioxide is injected as a solvent under certain temperature and pressure conditions to dissolve the target component.

[0003] However, existing extraction equipment has limitations and shortcomings when processing citrus peels. For example, in traditional supercritical CO2 extraction, initial citrus peel fragmentation is typically achieved through simple cutting. This method results in a limited degree of fragmentation, resulting in insufficient exposure of the active ingredients within the citrus peel to the supercritical CO2 solvent, thereby reducing extraction efficiency and product quality. Furthermore, a single fragmentation method makes it difficult to achieve efficient pulverization of citrus peels, especially when high yield and high-quality essential oils are required. Existing equipment cannot provide sufficiently detailed and uniform fragmentation, affecting the purity and consistency of the final product. Summary of the Invention

[0004] The object of the present invention is to provide a device and process for extracting citrus essential oil using supercritical CO2 to solve the problems raised in the background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a device for extracting citrus essential oil with supercritical CO2, comprising an extraction tank with citrus peel to be extracted, a bracket frame for erecting the extraction tank provided on the peripheral side of the extraction tank, a tank cover provided on the top surface of the extraction tank, a stirring motor installed on the top surface of the tank cover, an output shaft of the stirring motor passes through the extraction tank and is fixed with a stirring shaft, a plurality of stirring and crushing blades are symmetrically provided on the upper peripheral side of the stirring shaft, a grinding lower pressure plate is provided on the lower part of the stirring shaft and is located at the lower part of the inner cavity of the extraction tank, at least two rectangular through grooves are symmetrically opened inside the grinding lower pressure plate, a rectangular lifting block is lifted and set in each of the rectangular through grooves, and a crushing cutting piece for crushing and cutting the citrus peel to be extracted is provided on the bottom surface of the rectangular lifting block.

[0006] Preferably, the top surface of the grinding lower platen is provided with a detachable platen cover by means of bolts, and the peripheral side of the grinding lower platen is connected to the inner wall of the extraction tank by means of a lifting positioning member.

[0007] Preferably, the lifting positioning member includes two T-shaped positioning sleeves symmetrically welded to the outer wall of the grinding lower pressure plate and two L-shaped positioning rods symmetrically welded to the inner wall of the extraction tank.

[0008] Preferably, the two L-shaped positioning rods are inserted into the sleeve of the T-shaped positioning sleeve at one end away from the inner wall of the extraction tank, so that when the grinding lower pressure plate is raised or lowered, the T-shaped positioning sleeve is driven to move up and down around the L-shaped positioning rod for the longitudinal lifting and positioning of the grinding lower pressure plate.

[0009] Preferably, in this solution, a detachable top block is embedded in the middle of the top of each rectangular through slot, and a waterproof junction box extending into the rectangular through slot is installed on the bottom surface of the detachable top block. An electric lifting rod is installed on the bottom surface of the waterproof junction box, and the bottom lifting end of the electric lifting rod is fixedly connected to the rectangular lifting block.

[0010] Preferably, in this solution, an external thread path is provided on the peripheral side of the bottom end of the stirring shaft, and an internal thread path threadedly connected to the external thread path is provided on the longitudinal center axis of the grinding lower pressure plate and the detachable plate cover.

[0011] Preferably, the crushing cutter element includes a transverse cutting blade welded to one side of the bottom surface of the rectangular lifting block, a transverse base welded to the other side of the bottom surface of the rectangular lifting block, and a plurality of longitudinal cutting blades equidistantly welded to the bottom surface of the transverse base.

[0012] Preferably, a drive motor is installed on the outside of the bracket frame, and the output shaft of the drive motor is connected to a connecting block welded to the outer wall of the extraction tank, so that the drive motor can drive the extraction tank to swing left and right.

[0013] Preferably, a support buffer assembly is provided directly below the extraction tank and at the bottom of the bracket frame. The support buffer assembly includes a hydraulic lifting column for supporting the extraction tank when rocking and mixing are not required, and a buffer air spring for providing support, buffering and shock absorption for the extraction tank.

[0014] A process for extracting citrus essential oil using supercritical CO2 comprises the following steps:

[0015] S1. Wash fresh citrus peels and pour them into an extraction tank for crushing pretreatment. Turn on the stirring motor, which drives the stirring shaft to rotate, and the grinding lower pressure plate begins to rise and fall. When the grinding lower pressure plate descends, it directly applies pressure to the citrus peels at the bottom of the extraction tank to crush them;

[0016] S2, the rectangular lifting block can move up and down, and the horizontal cutting blade and the vertical cutting blade fixed on the bottom surface of the rectangular lifting block can cut the citrus peel from different directions;

[0017] S3. Applying supercritical CO2 fluid to the crushed pretreated citrus peel raw material, wherein the temperature of the supercritical CO2 fluid is controlled between 35° C. and 45° C., the pressure is maintained in the range of 20 MPa to 30 MPa, and the CO2 flow rate is set to 20 kg to 30 kg per hour;

[0018] S4. Pulse pressure regulation is applied to the supercritical CO2 fluid during the extraction process, i.e., the pressure is periodically increased or decreased by no more than ±2 MPa on a constant pressure basis, with a frequency ranging from once to five times per minute;

[0019] S5. After a preset time, the supercritical CO2 fluid containing the citrus essential oil is introduced into at least two separators arranged in series or parallel, wherein the operating conditions of the first separator are to reduce the temperature to 25° C. to 35° C. and maintain a low pressure to allow some lighter components to be separated; the second separator is further operated to adjust the temperature and pressure conditions to ensure that the remaining active ingredients are completely precipitated;

[0020] S6. Collecting the citrus essential oil obtained from the separator and performing post-processing on the citrus essential oil to ultimately obtain a high-quality citrus essential oil product;

[0021] S7. Use a combination of heat exchangers and energy-saving compressors to achieve the recycling of CO2.

[0022] Compared with the prior art, the technical effects and advantages of the present invention are:

[0023] This supercritical CO2 extraction device for citrus essential oils incorporates a grinding lower platen and a rectangular lifting block within it. These two elements work together to initially cut the citrus peels before further crushing them through the grinding lower platen's crushing and the cutting elements driven by the rectangular lifting block. This dual crushing method significantly improves the degree of citrus peel fragmentation and increases the effective contact area between the supercritical CO2 solvent and the citrus peels, significantly enhancing the efficiency and quality of essential oil extraction.

[0024] The rectangular lifting block is matched with the rectangular through slot, which can crush the materials by lowering the grinding plate, or further crush them by extending the crushing cutter, thus increasing the flexibility of the processing method.

[0025] The horizontal and vertical blades cut the citrus peels from different directions, improving shredding efficiency. The design of the clamping rubber buffer and buffer spring helps stabilize these cutters and reduce the risk of damage from collisions. The presence of the clamping rubber buffer and buffer spring ensures the stability of the cutters during operation, extending their service life and maintaining excellent cutting performance.

[0026] The motor-driven extraction tank rocking motion promotes thorough mixing of the materials within. This dynamic mixing, particularly for the initially crushed citrus peels, helps to more thoroughly break the material down and enhance extraction efficiency. After rocking mixing, the peels are then subjected to a secondary crushing process by internal pulverizing blades, further enhancing the citrus peels' fragmentation and, consequently, improving the extraction rate and purity of the essential oils. This motor-driven rocking mixing not only promotes thorough mixing but also unexpectedly achieves a secondary crushing effect. The rocking motion causes the peels to tumble continuously within the tank, increasing their contact with the pulverizing blades and further refining the material particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a structural schematic diagram of the present invention;

[0029] Figure 2 It is a structural schematic diagram of the support and buffer assembly of the present invention;

[0030] Figure 3 This is a schematic diagram of the split structure of the buffer tray of the present invention;

[0031] Figure 4 For the present invention Figure 1 Schematic diagram of the enlarged structure at A in the middle;

[0032] Figure 5 Schematic diagram of the installation structure of the stirring shaft of the present invention;

[0033] Figure 6 Schematic diagram of the installation structure of the grinding lower platen of the present invention;

[0034] Figure 7 Schematic diagram of the disassembled structure of the grinding lower platen and the detachable platen cover of the present invention;

[0035] Figure 8 Schematic diagram of the connection structure of the rectangular lifting block of the present invention

[0036] Figure 9 This is a schematic structural diagram of the clamping rubber buffer block of the present invention;

[0037] Figure 10 The present invention is a flow chart of a process for extracting citrus essential oil using supercritical CO2.

[0038] Description of reference numerals:

[0039] Figure: 1, extraction tank; 2, tank cover; 3, stirring motor; 4, horizontal support base frame; 5, vertical U-shaped frame; 6, moving wheel; 7, electric control box; 8, push-pull handrail; 9, support beam; 10, support buffer assembly; 11, support chassis; 12, hydraulic lifting column; 13, lifting support plate; 14, buffer air spring; 15, buffer plate; 16, silicone pad; 17, first positioning rod; 18, second positioning rod; 19, connecting block; 20, U-shaped locking block; 21, first locking bolt; 22, second locking bolt Tighten the bolts; 23. Drive motor; 24. Stirring shaft; 25. Stirring and crushing blade; 26. Grinding lower pressure plate; 27. Removable plate cover; 28. External thread; 29. ​​Limiting ring; 30. T-type positioning sleeve; 31. L-type positioning rod; 32. Internal thread; 33. Rectangular through slot; 34. Removable top block; 35. Waterproof junction box; 36. Electric lifting rod; 37. Rectangular lifting block; 38. Horizontal cutting blade; 39. Horizontal base; 40. Vertical cutting blade; 41. Clamping rubber buffer block; 42. Buffer spring. DETAILED DESCRIPTION

[0040] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without one or more of these details. In other instances, certain technical features well known in the art are not described to avoid confusion with the present invention.

[0041] Unless otherwise defined, the directions of up, down, left, right, front, back, inside and outside involved in this document are based on the directions of up, down, left, right, front, back, inside and outside shown in the figures of the present invention, and are explained here together.

[0042] This embodiment provides Figures 1 to 10The device for extracting citrus essential oil with supercritical CO2 shown in the figure includes an extraction tank 1 containing citrus peel to be extracted, a bracket frame for mounting the extraction tank 1 is provided on the periphery of the extraction tank 1, a tank cover 2 is provided on the top surface of the extraction tank 1, a stirring motor 3 is installed on the top surface of the tank cover 2, the output shaft of the stirring motor 3 passes through the extraction tank 1 and is fixed with a stirring shaft 24, a plurality of stirring and crushing blades 25 are symmetrically provided on the periphery of the upper part of the stirring shaft 24, and a grinding lower pressure plate 2 is provided on the lower part of the stirring shaft 24 and is located at the lower part of the inner cavity of the extraction tank 1. 6. At least two rectangular through-grooves 33 are symmetrically provided inside the grinding lower plate 26. A rectangular lifting block 37 is provided in each rectangular through-grooves 33 for lifting. The bottom surface of the rectangular lifting block 37 is provided with a crushing cutter for crushing and cutting the citrus peel to be extracted. When the grinding lower plate 26 descends, the citrus peel at the bottom of the inner cavity of the extraction tank 1 is crushed. At the same time, the internal rectangular lifting block 37 descends in the rectangular through-grooves 33, driving the crushing cutter to descend and cut the citrus peel. This dual crushing and grinding structure can quickly improve the extraction efficiency and quality of the citrus peel.

[0043] In this embodiment, a detachable plate cover 27 is mounted on the top surface of the grinding lower platen 26 by bolts, and the peripheral side of the grinding lower platen 26 is connected to the inner wall of the extraction tank 1 by a lifting positioning member.

[0044] In this embodiment, the lifting positioning member includes two T-shaped positioning sleeves 30 symmetrically welded to the outer wall of the grinding lower pressure plate 26 and two L-shaped positioning rods 31 symmetrically welded to the inner wall of the extraction tank 1 .

[0045] In this embodiment, the ends of the two L-shaped positioning rods 31 away from the inner wall of the extraction tank 1 are inserted into the sleeve of the T-shaped positioning sleeve 30, so that when the grinding lower pressure plate 26 is raised and lowered, the T-shaped positioning sleeve 30 is driven to move up and down around the L-shaped positioning rods 31 for the longitudinal lifting and positioning of the grinding lower pressure plate 26.

[0046] In this embodiment, a removable top block 34 is embedded in the center of the top of each rectangular slot 33. A waterproof junction box 35 is mounted on the bottom of the removable top block 34, extending into the rectangular slot 33. An electric lift rod 36 is mounted on the bottom of the waterproof junction box 35, and the bottom lifting end of the electric lift rod 36 is fixedly connected to a rectangular lift block 37. Each waterproof junction box 35 contains a battery that powers the adjacent electric lift rod 36. The electric lift rods 36 are wirelessly controlled to open and close via an external button. The removable top block 34 is bolted to the grinding lower platen 26. When the removable platen cover 27 is installed, the bottom surface of the removable platen 27 presses down on the top surface of the removable top block 34. The rectangular lift block 37 fits snugly within the rectangular slot 33. When the grinding lower platen 26 descends, the material is crushed by the lowering grinding platen 26, and further crushed by the extending shredder blade.

[0047] In this embodiment, an external thread 28 is provided around the bottom end of the agitator shaft 24. An internal thread 32, threadedly connected to the external thread 28, is provided along the longitudinal center axis of the grinding lower platen 26 and the removable platen cover 27. This allows the agitator motor 3 to drive the agitator shaft 24 forward and reverse, driving the grinding lower platen 26 and the removable platen cover 27 upward and downward. A limit ring 29 is welded above the external thread 28 and around the agitator shaft 24 to limit the lifting stroke of the removable platen cover 27.

[0048] In this embodiment, the crushing cutter assembly includes a transverse cutting blade 38 welded to one side of the bottom surface of the rectangular lifting block 37, a transverse base 39 welded to the other side of the bottom surface of the rectangular lifting block 37, and a plurality of longitudinal cutting blades 40 welded to the bottom surface of the transverse base 39 at equal intervals. This allows the transverse cutting blade 38 and the longitudinal cutting blade 40 to crush in different directions. A plurality of clamping rubber buffer blocks 41 are clamped and bonded between the transverse cutting blade 38 and the transverse base 39. Each clamping rubber buffer block 41 is embedded with a buffer spring 42, and the two ends of the buffer spring 42 elastically abut against the inner wall of the transverse base 39 and the transverse cutting blade 38 respectively. The design of the clamping rubber buffer block 41 and the buffer spring 42 contributes to the stable buffering of the transverse cutting blade 38, the transverse base 39, and the longitudinal cutting blade 40.

[0049] In this embodiment, a drive motor 23 is installed on the outside of the bracket frame, and the output shaft of the drive motor 23 is connected to the connecting block 19 welded to the outer wall of the extraction tank 1, so that the drive motor 23 can drive the extraction tank 1 to swing left and right, thereby mixing the citrus peels that have been preliminarily crushed inside. After the swinging and mixing, the citrus peels are crushed again by the internal crushing cutter parts to further improve the extraction effect.

[0050] In this embodiment, a support and buffer assembly 10 is located directly below the extraction tank 1 and at the bottom of the support frame. This assembly includes a hydraulic lift column 12, which supports the extraction tank 1 when rocking and mixing are not required, and an air spring 14, which provides support and shock absorption for the extraction tank 1. When rocking and mixing are required, the hydraulic lift column 12 and the air spring 14 are lowered synchronously to a safe distance, preventing the extraction tank 1 from rocking or shaking.

[0051] In this embodiment, the bracket frame includes a horizontal supporting base frame 4, an inverted vertical U-shaped frame 5 symmetrically welded on both sides of the top surface of the horizontal supporting base frame 4, movable wheels 6 fixed to the four corners of the bottom surface of the horizontal supporting base frame 4, an electric control box 7 installed in one of the vertical U-shaped frames 5, and two push-pull handrails 8 welded above the electric control box 7 and located on the outer wall of the vertical U-shaped frame 5. The electric control box 7 has a PLC for controlling the opening and closing of various electronic components.

[0052] In this embodiment, the support and buffering assembly 10 also includes support beams 9 symmetrically welded to the top surfaces of both sides of the horizontal support bottom frame 4 and a support chassis 11 welded between the two support beams 9. The hydraulic lifting column 12 is fixedly installed on the top surface of the support chassis 11. The top lifting end of the hydraulic lifting column 12 is welded with a lifting support plate 13. A plurality of buffer air springs 14 are fixed in a circular array on the top surface of the lifting support plate 13. The top ends of the plurality of buffer air springs 14 are fixed with a buffer plate 15. The top surface of the buffer plate 15 is bonded with a silicone pad 16. The silicone pad 16 elastically abuts against the bottom surface of the extraction tank 1. A plurality of first positioning rods 17 are welded in a circular array on the bottom surface of the lifting support plate 13. The first positioning rod 17 longitudinally penetrates the support chassis 11. A plurality of second positioning rods 18 are welded in a circular array on the bottom surface of the buffer plate 15. The second positioning rod 18 longitudinally penetrates the lifting support plate 13. The second positioning rod 18 is used to buffer the longitudinal movement of the buffer air spring 14. The first positioning rod 17 is used for longitudinal positioning of the hydraulic lifting column 12.

[0053] In this embodiment, the drive motor 23 is fixed to the outer wall of one of the vertical U-shaped frames 5, and the output shaft of the drive motor 23 passes through the vertical U-shaped frame 5 and is fixedly connected to the connecting block 19. When it is not necessary to swing the extraction tank 1, a U-shaped locking block 20 is installed between the connecting block 19 and the top surface of the vertical U-shaped frame 5. The U-shaped locking block 20 is connected to the connecting block 19 through a first locking bolt 21, and the U-shaped locking block 20 is connected to the vertical U-shaped frame 5 through a second locking bolt 22, thereby improving the stability of the extraction tank 1. When it is necessary to swing the extraction tank 1, the U-shaped locking block 20 is removed and the drive motor 23 can be turned on to swing and mix the extraction tank 1.

[0054] A process for extracting citrus essential oil using supercritical CO2 comprises the following steps:

[0055] S1. Wash fresh citrus peels and pour them into the extraction tank 1 for crushing pretreatment. Turn on the stirring motor 3, which drives the stirring shaft 24 to rotate, and the grinding lower platen 26 begins to rise and fall. When the grinding lower platen 26 descends, it directly applies pressure to the citrus peels at the bottom of the extraction tank 1 to crush them;

[0056] S2, the rectangular lifting block 37 can move up and down, and the horizontal cutting blade 38 and the longitudinal cutting blade 40 fixed on the bottom surface of the rectangular lifting block 37 can cut the citrus peel from different directions;

[0057] S3. Applying supercritical CO2 fluid to the crushed pretreated citrus peel raw material, wherein the temperature of the supercritical CO2 fluid is controlled between 35° C. and 45° C., the pressure is maintained in the range of 20 MPa to 30 MPa, and the CO2 flow rate is set to 20 kg to 30 kg per hour;

[0058] S4. Pulse pressure regulation is applied to the supercritical CO2 fluid during the extraction process, i.e., the pressure is periodically increased or decreased by no more than ±2 MPa on a constant pressure basis, with a frequency ranging from once to five times per minute, to promote material transfer and enhance the extraction effect;

[0059] S5. After a preset time (e.g., 60 minutes), the supercritical CO2 fluid containing the citrus essential oil is introduced into at least two separators arranged in series or in parallel, wherein the operating conditions of the first separator are to reduce the temperature to 25° C. to 35° C. and maintain a relatively low pressure to allow some of the lighter components to be separated; the second separator is further operated to adjust the temperature and pressure conditions to ensure that the remaining active ingredients are completely precipitated;

[0060] S6, collecting the citrus essential oil obtained from the separator, and performing post-processing such as filtering and clarifying on the citrus essential oil to ultimately obtain a high-quality citrus essential oil product;

[0061] S7. Combining heat exchangers with energy-saving compressors can achieve the recycling of CO2, reducing operating costs while minimizing environmental impact.

[0062] Working principle:

[0063] The device for extracting citrus essential oil with supercritical CO2 opens the tank lid 2 and places the citrus peel to be extracted into the extraction tank 1. Close and tighten the tank lid 2 to ensure sealing, and use the PLC control system in the electrical control box 7 to set the extraction parameters, including temperature, pressure, time, and whether rocking and mixing are required. Adjust the height of the hydraulic lifting column 12 as needed so that the buffer air spring 14 is in a position that does not affect rocking, start the stirring motor 3, and drive the stirring and crushing blade 25 to rotate through the stirring shaft 24 to perform preliminary cutting and crushing of the citrus peel to increase the material contact area in preparation for subsequent extraction. Start the stirring motor 3, and drive the stirring and crushing blade 25 to rotate through the stirring shaft 24 to perform preliminary cutting and crushing of the citrus peel to increase the material contact area in preparation for subsequent extraction.

[0064] As the extraction process progresses, the grinding lower platen 26 descends according to a pre-set sequence, crushing the citrus peels at the bottom. Simultaneously, the rectangular lifting block 37 within the rectangular slot 33 also descends, allowing the transverse cutting blades 38 and longitudinal cutting blades 40 mounted thereon to further cut and crush the citrus peels. This dual crushing mechanism significantly improves extraction efficiency. According to the set sequence, the grinding lower platen 26 begins to descend, and the rectangular lifting blocks 37, symmetrically positioned within the rectangular slot 33, rise and fall. As the grinding lower platen 26 descends, it directly applies pressure to the citrus peels at the bottom of the extraction tank 1, crushing them. A waterproof junction box 35 is mounted beneath the removable top block 34, nestled in the center of the top of the rectangular slot 33. This contains an electric lift rod 36. Controlled by a PLC system, the electric lift rod 36 independently drives the rectangular lifting block 37 up and down. Affixed to the bottom of the rectangular lifting block 37 are transverse cutting blades 38 and longitudinal cutting blades 40, which cut the citrus peels from different directions. The clamping rubber buffer block 41 and the buffer spring 42 ensure that the cutter element remains stable during the cutting process and reduces damage caused by vibration.

[0065] The hydraulic lifting column 12 in the support buffer assembly 10 is used to adjust the height of the extraction tank 1. When rocking and mixing are not required, the hydraulic lifting column 12 is raised, so that the buffer air spring 14 is in a supporting state; when rocking is required, the hydraulic lifting column 12 is lowered to a safe distance to avoid obstructing the rocking movement. The buffer air spring 14 is installed on the lifting support plate 13, and its top end is connected to the buffer plate 15, and elastically abuts against the bottom of the extraction tank 1 through the silicone pad 16. This can effectively absorb the impact force caused by rocking or other operations, protect the equipment and maintain smooth operation. The first positioning rod 17 and the second positioning rod 18 pass through the support chassis 11 and the lifting support plate 13 respectively, providing a precise longitudinal movement path for the hydraulic lifting column 12 and the buffer air spring 14 to ensure their stability and reliability.

[0066] Before rocking and mixing, it is first necessary to loosen the U-shaped locking block 20 between the connecting block 19 and the vertical U-shaped frame 5. This step is completed by the first locking bolt 21 and the second locking bolt 22 to release the freedom of the extraction tank 1. Once the U-shaped locking block 20 is removed, the drive motor 23 fixed to the outer wall of the vertical U-shaped frame 5 can be started. The output shaft of the motor directly drives the extraction tank 1 to rock left and right through the connecting block 19. The rocking action not only promotes the thorough mixing of the citrus peel, but also allows the already crushed material to be subjected to the action of the internal pulverizing and cutting elements again, achieving a more thorough crushing effect. This dynamic mixing helps to improve the extraction efficiency and quality.

[0067] When the extraction cycle is completed, all moving parts are stopped, the supercritical CO2 solvent in the extraction tank 1 is emptied, and the extracted essential oil is collected.

[0068] It should be noted that, in this article, relational terms such as one and two are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions. The sentence "including an element defined by ... does not exclude the presence of other identical elements in the process, method, article or device that includes the element."

[0069] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A device for extracting citrus essential oil using supercritical CO2, comprising an extraction tank (1) containing citrus peel to be extracted, a support frame for mounting the extraction tank (1) provided on the periphery of the extraction tank (1), and characterized in that: The top surface of the extraction tank (1) is provided with a tank cover (2), and a stirring motor (3) is installed on the top surface of the tank cover (2). The output shaft of the stirring motor (3) passes through the extraction tank (1) and is fixed with a stirring shaft (24). A plurality of stirring and crushing blades (25) are symmetrically provided around the upper side of the stirring shaft (24). The lower part of the stirring shaft (24) is located at the lower part of the inner cavity of the extraction tank (1) and is provided with a grinding lower pressure plate (26) for lifting. At least two rectangular through grooves (33) are symmetrically provided inside the grinding lower pressure plate (26), and a rectangular lifting block (37) is lifted and provided in each of the rectangular through grooves (33). The bottom surface of the rectangular lifting block (37) is provided with a crushing cutter for crushing and cutting the citrus peel to be extracted. The crushing cutter member comprises a transverse cutting blade (38) welded to one side of the bottom surface of the rectangular lifting block (37), a transverse base (39) welded to the other side of the bottom surface of the rectangular lifting block (37), and a plurality of longitudinal cutting blades (40) welded to the bottom surface of the transverse base (39) at equal intervals.

2. The device for supercritical CO2 extraction of citrus essential oil according to claim 1, characterized in that: A detachable disc cover (27) is mounted on the top surface of the grinding lower platen (26) via bolts, and the peripheral side of the grinding lower platen (26) is connected to the inner wall of the extraction tank (1) via a lifting positioning member.

3. The device for supercritical CO2 extraction of citrus essential oil according to claim 2, characterized in that: The lifting positioning member comprises two T-shaped positioning sleeves (30) symmetrically welded to the outer wall of the grinding lower pressure plate (26) and two L-shaped positioning rods (31) symmetrically welded to the inner wall of the extraction tank (1).

4. The apparatus for supercritical CO2 extraction of citrus essential oil according to claim 3, characterized in that: The ends of the two L-shaped positioning rods (31) away from the inner wall of the extraction tank (1) are inserted into the sleeve of the T-shaped positioning sleeve (30), so that when the grinding lower pressure plate (26) is raised or lowered, the T-shaped positioning sleeve (30) is driven to move up and down around the L-shaped positioning rods (31) for longitudinal lifting and positioning of the grinding lower pressure plate (26).

5. The apparatus for supercritical CO2 extraction of citrus essential oil according to claim 4, characterized in that: A detachable top block (34) is embedded in the middle of the top of each rectangular through slot (33); a waterproof junction box (35) extending into the rectangular through slot (33) is installed on the bottom surface of the detachable top block (34); an electric lifting rod (36) is installed on the bottom surface of the waterproof junction box (35); and the bottom lifting end of the electric lifting rod (36) is fixedly connected to the rectangular lifting block (37).

6. The apparatus for supercritical CO2 extraction of citrus essential oil according to claim 5, characterized in that: An external threaded path (28) is provided on the peripheral side of the bottom end of the stirring shaft (24), and an internal threaded path (32) threadedly connected to the external threaded path (28) is provided on the longitudinal center axis of the grinding lower pressure plate (26) and the detachable plate cover (27).

7. The apparatus for supercritical CO2 extraction of citrus essential oil according to claim 6, characterized in that: A drive motor (23) is installed on the outside of the bracket frame, and an output shaft of the drive motor (23) is connected to a connection block (19) welded to the outer wall of the extraction tank (1), so that the drive motor (23) can drive the extraction tank (1) to swing left and right.

8. The apparatus for supercritical CO2 extraction of citrus essential oil according to claim 7, characterized in that: A support buffer assembly (10) is provided directly below the extraction tank (1) and at the bottom of the support frame. The support buffer assembly (10) comprises a hydraulic lifting column (12) for supporting the extraction tank (1) when rocking and mixing are not required, and a buffer air spring (14) for providing support, buffering and shock absorption for the extraction tank (1).

9. A process for extracting citrus essential oil by supercritical CO2, using the apparatus for extracting citrus essential oil by supercritical CO2 according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Wash fresh citrus peels and pour them into the extraction tank (1) for crushing pretreatment. Turn on the stirring motor (3). The stirring motor (3) drives the stirring shaft (24) to rotate, and the grinding lower pressure plate (26) starts to rise and fall. When the grinding lower pressure plate (26) descends, it directly applies pressure to the citrus peels at the bottom of the extraction tank (1) to crush them. S2, the rectangular lifting block (37) can move up and down, and the horizontal cutting blade (38) and the longitudinal cutting blade (40) fixed on the bottom surface of the rectangular lifting block (37) can cut the citrus peel from different directions; S3, applying supercritical CO2 fluid to the crushed pretreated citrus peel raw material, wherein the temperature of the supercritical CO2 fluid is controlled between 35°C and 45°C, the pressure is maintained in the range of 20MPa to 30MPa, and the CO2 flow rate is set to 20kg to 30kg per hour; S4. Pulse pressure regulation is applied to the supercritical CO2 fluid during the extraction process, i.e., the pressure is periodically increased or decreased by no more than ±2 MPa on a constant pressure basis, with a frequency ranging from once to five times per minute; S5. After a preset time, the supercritical CO2 fluid containing the citrus essential oil is introduced into at least two separators arranged in series, wherein the operating conditions of the first separator are to reduce the temperature to 25°C to 35°C and maintain a relatively low pressure to separate some of the lighter components; the second separator is further adjusted to adjust the temperature and pressure conditions to ensure that the remaining active ingredients are completely precipitated; S6. Collecting the citrus essential oil obtained from the separator and performing post-processing on the citrus essential oil to ultimately obtain a high-quality citrus essential oil product; S7. Use a combination of heat exchangers and energy-saving compressors to achieve the recycling of CO2.

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