Device for extracting residual oil and tea saponin from camellia seed cakes

Abstract

The invention provides a device for extracting residual oil and tea saponin in camellia seed cakes, and belongs to the technical field of camellia seed cake processing.The extraction device comprises an extraction tank, a liquid capturing pipe, an upper electrode plate and a lower electrode plate, the liquid capturing pipe can extrude raw materials and generate high pressure when driving the upper electrode plate to move downwards in the extraction tank, and the lower electrode plate is driven by the liquid capturing pipe to move downwards in the extraction tank; ohmic heat is generated in the raw materials after the upper electrode plate and the lower electrode plate are electrified, water in the raw materials is in a subcritical state under the high-temperature and high-pressure environment, and the subcritical water can better dissolve and extract residual oil and tea saponin. The device adopts an ohmic heating mode, is not limited by heat transfer area and temperature difference, is high in heating rate and heat efficiency, and does not need an external heat exchanger and a high-pressure conveying system. In addition, the device can drive the porous upper electrode plate to extrude the material through the liquid trapping pipe, solid-liquid separation is synchronously carried out at subcritical temperature and pressure, and an extract is prevented from returning to a solid phase.

Description

Technical Field

[0001] The invention belongs to the technical field of camellia seed cake processing, and more specifically, relates to a device for extracting residual oil and tea saponin from camellia seed cake. Background Art

[0002] At present, my country's annual tea seed production has exceeded 4.2 million tons, and the output of tea cakes obtained after oil pressing has reached more than 3 million tons. The macro-components such as residual oil, tea saponin, protein, polysaccharides, etc. in tea cakes have high utilization value. If not utilized, it will cause a huge waste of resources.

[0003] At present, the extraction of residual oil and tea saponin from camellia seed cake in industry mostly adopts a step-by-step extraction process, that is, extracting residual oil first and then extracting tea saponin. The commonly used processes are: hydrocarbon-alcohol two-stage extraction, extracting oil and tea saponin respectively; hydrocarbon-water two-stage extraction, extracting oil and tea saponin respectively. However, these methods involve the use of flammable and explosive organic solvents, the process is complicated, and the safety and environmental protection are insufficient. In view of the characteristics of subcritical water, continuous extraction from water-soluble substances to fat-soluble substances can be achieved, and it is expected to implement the simultaneous extraction of residual oil and tea saponin in camellia seed cake.

[0004] Subcritical water extraction needs to be carried out under high temperature and high pressure. Existing devices have three major limitations: (1) The heating method is mainly indirect heating, which is limited by the heat exchange area and temperature difference of the tank, with low heat transfer efficiency and slow heating rate; while the direct heating method of subcritical water requires the configuration of external heat exchangers, high-pressure pumps and pipeline systems, which greatly increases the complexity of the device; (2) Limited by the sealing requirements of the high-pressure tank, only magnetic stirring or no stirring can be used, making it difficult to improve the heat transfer and mass transfer efficiency of the extraction operation, resulting in poor material temperature uniformity and insufficient extraction of the target component. (3) The tank can only meet the basic requirements of extracting the target component. After extraction, it is necessary to use an external separation device to achieve solid-liquid separation, so it is impossible to achieve solid-liquid separation under subcritical conditions. Summary of the invention

[0005] The invention aims to provide a device for extracting residual oil and tea saponin from camellia seed cakes, so as to solve the problems of low heating efficiency, complex structure and inability to achieve solid-liquid separation synchronously in the existing extraction device.

[0006] In order to achieve the above object, the present invention provides a device for extracting residual oil and tea saponin from camellia seed cake, comprising:

[0007] An extraction tank, which is an insulating cylinder and has a feed inlet at the top;

[0008] A liquid collecting tube, the lower end of which is movably inserted into the top of the extraction tank, and the upper end of which extends outside the extraction tank and is provided with an extraction liquid discharge valve;

[0009] An upper electrode plate, the outer periphery of which matches the inner periphery of the extraction tank, the upper electrode plate is connected to one end of the liquid collecting tube, and the upper electrode plate is provided with mesh holes to allow the extraction tank to communicate with the liquid collecting tube;

[0010] A lower electrode plate is arranged above the bottom of the extraction tank.

[0011] Optionally, the lower electrode plate comprises:

[0012] An insulating porous mesh plate, the outer periphery of which is connected to the inner periphery of the extraction tank;

[0013] A circular conductive sheet, the diameter of which is smaller than the inner diameter of the extraction tank, and the circular conductive sheet is centrally arranged on the lower surface of the insulating porous mesh plate.

[0014] Optionally, a discharge valve is provided at the bottom of the extraction tank, the discharge valve can be opened or closed, and the lower electrode plate is arranged on the discharge valve.

[0015] Optionally, the device for extracting residual oil and tea saponin from camellia seed cakes further comprises:

[0016] A driving device is connected to the liquid collecting tube and is used to drive the liquid collecting tube to move up and down.

[0017] Optionally, a threaded sealing section is provided on the top of the extraction tank, the liquid collecting tube is threadedly connected to the threaded sealing section, and the driving device can drive the liquid collecting tube to rotate so that the liquid collecting tube moves up and down.

[0018] Optionally, the liquid collecting tube is connected to the upper electrode plate via a connecting section, and the connecting section tapers from bottom to top.

[0019] Optionally, the aperture of the mesh is not greater than 0.38 mm.

[0020] Optionally, the liquid collecting tube is provided with a conductive slip ring, and the conductive slip ring is connected to the upper electrode plate 4 .

[0021] Optionally, the number of threads of the threaded sealing section is not less than 16.

[0022] Optionally, a sealing ring is provided on the edge of the upper electrode plate.

[0023] The beneficial effects of the present invention are: providing a device for extracting residual oil and tea saponin from oil-tea camellia seed cake, comprising: an extraction tank, a liquid collection tube, an upper electrode plate and a lower electrode plate. When the liquid collection tube drives the upper electrode plate to move downward in the extraction tank, it can squeeze the raw material and ensure the density and dielectric uniformity of the material layer. After the upper electrode plate and the lower electrode plate are energized, ohmic heat is generated inside the raw material, which is not limited by the heat transfer area and temperature difference, has a high heating rate and high thermal efficiency, and does not require an external heat exchanger and a high-pressure transmission system. Based on ohmic heating, the water in the material layer is in a subcritical state of high temperature and high pressure, which can efficiently dissolve tea saponin, and the high concentration of tea saponin causes the residual oil to be eluted and enter the liquid phase in an emulsified form. In addition, the hot and cold partitions in the extraction tank are constructed based on non-full-size electrode plates, and the insulating porous plate under the material layer is combined to form a circulation channel, so as to realize natural convection and mass transfer enhancement in the extraction tank, and eliminate the problem of material consolidation and coking on the surface of the electrode plate. In addition, the device drives the porous upper electrode plate to squeeze the material through the liquid collection tube, which can achieve solid-liquid separation under subcritical temperature and pressure, so that high concentrations of tea saponin and oil are retained in the liquid phase, achieving efficient extraction of the target components.

[0024] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0026] Figure 1 One of the schematic structural diagrams of the device for extracting residual oil and tea saponin from camellia seed cake according to the first embodiment of the present invention is shown.

[0027] Figure 2 The second schematic structural diagram of the device for extracting residual oil and tea saponin from camellia seed cake according to the first embodiment of the present invention is shown.

[0028] Figure 3 The third schematic structural diagram of the device for extracting residual oil and tea saponin from camellia seed cake according to the first embodiment of the present invention is shown.

[0029] Figure 4 A fourth schematic structural diagram of the device for extracting residual oil and tea saponin from camellia seed cake according to the first embodiment of the present invention is shown.

[0030] Figure 5 A schematic diagram showing the convection of water in an extraction tank according to the first embodiment of the present invention is shown.

[0031] Description of reference numerals:

[0032] 1. Extraction liquid discharge valve; 2. Liquid collecting tube; 3. Threaded sealing section; 4. Upper electrode plate; 41. Mesh; 5. Extraction tank; 6. Lower electrode plate; 61. Insulating porous mesh plate; 62. Round conductive sheet; 7. Discharge valve; 8. Feed inlet; 9. Driving device. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0034] Embodiment 1:

[0035] like Figure 1-4 As shown, this embodiment provides a device for extracting residual oil and tea saponin from tea seed cake, comprising:

[0036] The extraction tank 5 is an insulating cylinder and has a feed port 8 at the top;

[0037] A liquid collecting tube 2, the lower end of which is movably inserted into the top of the extraction tank 5, and the upper end of which extends to the outside of the extraction tank 5 and is provided with an extraction liquid discharge valve 1;

[0038] An upper electrode plate 4, the outer periphery of which matches the inner periphery of the extraction tank 5, the upper electrode plate 4 is connected to one end of the liquid collecting tube 2, the upper electrode plate 4 is provided with a mesh 41 to allow the liquid collecting tube to communicate with the liquid collecting tube 2, and the liquid collecting tube 2 can drive the upper electrode plate 4 to perform piston motion in the extraction tank 5;

[0039] The lower electrode plate 6 is arranged above the bottom of the extraction tank 5 .

[0040] In this embodiment, the extraction tank 5 is a vertical pressure-resistant straight cylinder tank with a smooth and insulated inner wall, and a feed port 8 is provided on the side wall; the upper electrode plate 4 is composed of a rigid outer ring and a conductive mesh in the middle, is horizontally placed in the extraction tank 5 and can move up and down, and its mesh surface is also the filter surface for solid-liquid separation during isothermal pressing, and the mesh area can be increased as much as possible, and the strength of the upper electrode plate 4 can be improved by reinforcing ribs; the lower electrode plate 6 is located at the bottom of the extraction tank 5 and is parallel to the upper electrode plate 4; the liquid collection tube 2 is vertically inserted into the extraction tank 5 and connected to the upper electrode plate 4, and the liquid collection tube 2 can move up and down in the extraction tank 5 and drive the upper electrode plate 4 to do piston movement.

[0041] The device is used as follows:

[0042] Feeding stage: Figure 1As shown, the liquid collecting tube 2 is raised, and the liquid collecting tube 2 drives the upper electrode plate 4 to move upward until the upper electrode plate 4 is located above the feed port 8, and the raw materials enter the extraction tank 5 through the feed port 8. Then the liquid collecting tube 2 is lowered until the electrode plate 4 is located at a suitable position below the feed port 8, and a certain amount of water is added through the feed port 8 to form a liquid seal.

[0043] Extraction process: Figure 2 As shown, the upper electrode plate 4 and the lower electrode plate 6 are powered on, and after ohmic heating, the water in the extraction tank 5 reaches a subcritical state, and the gas is discharged through the extraction liquid discharge valve 1 to stabilize the pressure in the tank. After heating for a period of time, the target component enters the liquid phase from the solid phase, and the extraction ends.

[0044] Pressing process: Figure 3 As shown, the liquid collecting tube 2 is adjusted downward, the material in the extraction tank 5 is squeezed by the upper electrode plate 4, and the liquid phase therein enters the liquid collecting tube 2 through the mesh 41 of the upper electrode plate 4 and is discharged through the extraction liquid discharge valve 1.

[0045] Specifically, water has a strong polarity at room temperature and pressure. In a subcritical state, the hydrogen bonds of water open or weaken as the temperature rises. Therefore, by controlling the temperature and pressure of subcritical water and changing the polarity of water, the extraction of natural products from water-soluble to fat-soluble active ingredients can be achieved. Therefore, this embodiment uses subcritical water as an extractant to simultaneously extract the residual oil and tea saponin in the oil-tea camellia seed cake. Compared with ordinary water as an extractant, the tea saponin solubility is higher when subcritical water is used as an extractant, making the residual oil in the cake easier to elute and stabilized in the subcritical water phase in an emulsified form, so a lower liquid-to-solid ratio can be used, and the recovery cost of the extractant is lower.

[0046] Traditional direct heating (such as using air, steam, etc. as heating medium) or indirect heating (heat transfer through heating wall surface) is difficult to achieve precise temperature control and uniform heating; the heat transferred in the form of radiation is often preferentially absorbed by shallow materials, and the heating is also uneven. Ohmic heating is heating using the electrical conductivity of the material. When the current passes through the material, the electrical energy is converted into thermal energy inside the material, thereby directly and evenly heating it. This process is not limited by the heating area and temperature difference. The equipment structure is compact and the thermal energy utilization rate is high. In this embodiment, the upper electrode plate 4 and the lower electrode plate 6 are energized to generate ohmic heat inside the raw material, and the high temperature and high pressure environment makes the water in the raw material in a subcritical state.

[0047] Although subcritical water can improve the dissolution rate of residual oil and tea saponin by using it as an extractant, if the solid-liquid separation after extraction cannot maintain the subcritical state, tea saponin will be precipitated from the liquid phase due to reduced solubility. At the same time, the oil that enters the liquid phase due to the emulsification of tea saponin will also return to the solid phase from the liquid phase due to the precipitation of tea saponin from the liquid phase, which will inevitably lead to a reduction in the extraction rate of the target component, so that the advantages of subcritical water extraction are not fully utilized. In this embodiment, the porous upper electrode plate 4 is driven by the liquid capture tube 2 to extrude the material to ensure that the solid and liquid phases are separated more thoroughly at the extraction temperature.

[0048] Optionally, the lower electrode plate 6 comprises:

[0049] An insulating porous mesh plate 61, the outer periphery of the insulating porous mesh plate 61 is connected to the inner periphery of the extraction tank 5;

[0050] The circular conductive sheet 62 has a diameter smaller than the inner diameter of the extraction tank 5 , and the circular conductive sheet 62 is centrally disposed on the lower surface of the insulating porous mesh plate 61 .

[0051] Specifically, since there is no stirring device in the extraction tank 5, as the process proceeds, the oil tea cake particles settle, causing the material near the lower electrode plate 6 to lose moisture. If the moisture is not replenished, it will dry out, and even affect the conductivity and become unable to heat. In this embodiment, first, the diameter of the circular conductive sheet 62 is set to be smaller than the inner diameter of the extraction tank 5, so that the material layer in the projection area directly above the conductive sheet 62 is placed in the electric field to obtain more current distribution and higher temperature; and the subcritical water temperature in the annular space outside the projection area is lower, so that there is a temperature difference and density difference between the two areas, which constitutes the driving force of natural convection. Secondly, an insulating porous mesh plate 61 is set above the circular conductive sheet 62, which not only avoids direct contact between the oil tea cake material layer and the electrode plate, but also maintains a circulating water flow channel under the oil tea cake material layer to form an unobstructed natural convection path. Based on this setting, not only the problem of drying of the material on the surface of the lower electrode plate 6 is solved, but also the heat and mass transfer efficiency in the extraction tank 5 is higher, and the extraction of the target component is more complete. The natural convection of water in the extraction tank 5 is as shown in the figure. Figure 5 shown.

[0052] Optionally, a discharge valve 7 is provided at the bottom of the extraction tank 5 , and the discharge valve 7 can be opened or closed, and the lower electrode plate 6 is arranged on the discharge valve 7 .

[0053] Specifically, the lower electrode plate 6 is fixed to the inner side of the discharge valve, and opens and closes with the discharge valve 7. Figure 4 As shown, after the pressing is completed, the discharge valve 7 of the extraction tank 5 can be opened, and the extraction residue will be discharged from the discharge valve 7.

[0054] Optionally, the device for extracting residual oil and tea saponin from camellia seed cakes further comprises:

[0055] The driving device 9 is connected to the liquid collecting tube 2 and is used to drive the liquid collecting tube 2 to move up and down.

[0056] Optionally, a threaded sealing section 3 is provided on the top of the extraction tank 5, and the liquid collecting tube 2 is threadedly connected to the threaded sealing section 3, and the driving device 9 can drive the liquid collecting tube 2 to rotate so that the liquid collecting tube 2 moves up and down.

[0057] Specifically, the threaded sealing section 3 is placed on the top of the extraction tank, and its internal thread is nested with the external thread of the liquid collecting tube 2; the upper part of the liquid collecting tube 2 is connected to the driving device 9, which provides power for the liquid collecting tube 2 to be screwed in or out.

[0058] Optionally, the liquid collecting tube 2 is connected to the upper electrode plate 4 via a connecting section 21 , and the connecting section tapers from bottom to top.

[0059] Specifically, the connecting section 21 is a conical tube, and the diameter of the lower end of the connecting section 21 is slightly smaller than the inner diameter of the extraction tank 5 and larger than the diameter of the circular mesh of the upper electrode plate 4 .

[0060] Optionally, the aperture of the mesh 41 is not greater than 0.38 mm.

[0061] Specifically, if the pore size of the mesh 41 is too large, insufficient solid-liquid separation may result. Experiments have shown that the pore size of the mesh 41 should not be greater than 0.38 mm.

[0062] Optionally, the liquid collecting tube 2 is provided with a conductive slip ring, and the conductive slip ring is connected to the upper electrode plate 4 .

[0063] In this embodiment, the liquid collecting tube 2 is a conductor, one pole of the external AC power source is introduced through a conductive slip ring fixed on the liquid collecting tube 2, and is connected to the upper electrode plate 4 through the liquid collecting tube 2. The other pole of the external AC power source is introduced through the discharge valve 7 and is connected to the lower electrode plate 6.

[0064] Optionally, the number of threads of the threaded sealing section 3 is not less than 16.

[0065] Specifically, the thread sealing section 3 plays two main roles: first, it uses the high viscosity sealing oil in the thread slit to achieve the necessary sealing conditions, and second, it provides a precise rotation track for the liquid collection tube. Experiments have shown that the number of threads in the thread sealing section 3 should not be less than 16.

[0066] Optionally, a sealing ring is provided on the edge of the upper electrode plate 4 .

[0067] Specifically, a sealing ring is provided on the outer side of the rigid outer ring of the upper electrode plate 4 so as to keep it in close contact with the inner wall of the extraction tank 5 during the rotational movement.

[0068] Embodiment 2:

[0069] This embodiment provides a method for using a device for extracting residual oil and tea saponin from camellia seed cakes, using the extraction device in Embodiment 1, including the following steps:

[0070] Feeding stage: The liquid collecting tube 2 is rotated upward by the driving device 9, and the liquid collecting tube 2 drives the upper electrode plate 4 to move upward until the upper electrode plate is located above the feed port 8, and the raw materials with a liquid-solid ratio of 1:1 enter the extraction tank 5 through the feed port 8. Then, the liquid collecting tube 2 is rotated downward by the driving device 9 to a suitable position below the feed port 8, and a certain amount of water is added through the feed port 8 to form a liquid seal.

[0071] Extraction stage: Turn on the power supply, after ohmic heating, the subcritical water temperature in the tank reaches 150°C, and the gas is discharged through the extraction liquid discharge valve 1 to stabilize the pressure in the tank. After heating for 40 minutes, the extraction is completed.

[0072] Squeezing stage: The liquid collecting tube 2 is adjusted downward by the driving device 9, and the material in the tank is squeezed by the upper electrode plate 4. The liquid phase enters the liquid collecting tube 2 through the holes of the upper electrode plate 4 and is discharged through the extraction liquid discharge valve 1.

[0073] Discharging stage: Open the bottom valve of the extraction tank, and the extraction residue will be discharged from the discharging valve 7.

[0074] After testing, the tea saponin content in the extract can reach 0.1g / mL, and the oil content can reach 0.04g / mL.

[0075] Comparative Example 1:

[0076] The difference between this comparative example and Example 2 is that the water temperature in the tank during the extraction process is 75°C (non-subcritical state). After the extraction is completed, the extract is tested and the tea saponin content is 0.0014g / mL and the oil content is 0.0005g / mL. It can be seen that the good solubility of subcritical water requires less amount of extractant when extracting residual oil and tea saponin, and the low liquid-to-solid ratio makes the subsequent recovery process of the extractant lower in processing volume, lower in energy consumption, and more economical.

[0077] Comparative Example 2:

[0078] The difference between this comparative example and the second embodiment is that the diameter of the circular conductive sheet 62 is equal to the inner diameter of the extraction tank 5 and there is no porous insulating mesh. After ohmic heating, the circuit pressure and current are normal at first, but after more than ten minutes, the current is very small, the system cannot maintain a high temperature state, and the extraction fails. When the equipment is disassembled, it is found that the material layer close to the lower electrode plate has dried up. It can be seen that setting the diameter of the circular conductive sheet 62 to be smaller than the inner diameter of the extraction tank 5 and setting a porous insulating mesh can solve the problem of material drying up on the surface of the lower electrode plate 6.

[0079] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A device for extracting residual oil and tea saponin from camellia seed cake, characterized in that: include: An extraction tank (5), wherein the extraction tank (5) is an insulating cylinder and is provided with a feed inlet (8) at the top; a liquid collecting tube (2), the lower end of the liquid collecting tube (2) being movably inserted into the top of the extraction tank (5), the upper end of the liquid collecting tube (2) extending outside the extraction tank (5) and being provided with an extraction liquid discharge valve (1); an upper electrode plate (4), the outer periphery of the upper electrode plate (4) being matched with the inner periphery of the extraction tank (5), the upper electrode plate (4) being connected to one end of the liquid collecting tube (2), and the upper electrode plate (4) being provided with a mesh (41) so that the extraction tank (5) and the liquid collecting tube (2) are in communication; A lower electrode plate (6), wherein the lower electrode plate (6) is arranged at the bottom of the extraction tank (5).

2. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: The lower electrode plate (6) comprises: An insulating porous mesh plate (61), the outer periphery of the insulating porous mesh plate (61) being connected to the inner periphery of the extraction tank (5); A circular conductive sheet (62), the diameter of which is smaller than the inner diameter of the extraction tank (5), and the circular conductive sheet (62) is centrally arranged on the lower surface of the insulating porous mesh plate (61).

3. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: A discharge valve (7) is provided at the bottom of the extraction tank (5), and the discharge valve (7) can be opened or closed. The lower electrode plate (6) is arranged on the discharge valve (7).

4. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: Also includes: A driving device (9), the driving device (9) is connected to the liquid collecting tube (2) and is used to drive the liquid collecting tube (2) to move up and down.

5. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 4, characterized in that: The top of the extraction tank (5) is provided with a threaded sealing section (3), the liquid collecting tube (2) is threadedly connected to the threaded sealing section (3), and the driving device (9) can drive the liquid collecting tube (2) to rotate so that the liquid collecting tube (2) moves up and down.

6. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: The liquid collecting tube (2) is connected to the upper electrode plate (4) via a connecting section (21), and the connecting section tapers from bottom to top.

7. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: The aperture of the mesh (41) is no greater than 0.38 mm.

8. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: The liquid collecting tube (2) is provided with a conductive slip ring, and the conductive slip ring is connected to the upper electrode plate (4).

9. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 5, characterized in that: The number of threads of the threaded sealing section (3) is not less than 16.

10. The device for extracting residual oil and tea saponin from camellia seed cake according to claim 1, characterized in that: A sealing ring is provided at the edge of the upper electrode plate.

Images