Supercritical extraction separation kettle, extraction system and extraction method

Abstract

The present invention discloses a supercritical extraction separation kettle, an extraction system and an extraction method. The supercritical extraction separation kettle comprises a kettle body, a top cover, and an annular extraction layer, an annular porous medium layer and a cyclone separator which are sequentially arranged from the outside to the inside of the kettle body. On the one hand, this annular layered structure enables the extractant to complete the extraction in the form of an inward-rotating flow, thereby increasing the contact area between the extractant and the object to be extracted during the flow process, and greatly improving the extraction yield; on the other hand, it increases the space utilization rate inside the extraction kettle, avoiding the common wall flow problem in the supercritical extraction process; at the same time, by designing the direction of the air inlet and setting an arc-shaped guide plate, the flow field inside the extraction separation kettle is made more uniform and stable. The supercritical extraction separation kettle body of the present invention has three functions of extraction, pressure reduction and separation and purification, and can achieve high-quality and efficient extraction of bioactive components, as well as the recycling and reuse of the extractant.

Description

Technical Field

[0001] The invention relates to the technical field of supercritical extraction, in particular to a supercritical extraction separation kettle and an extraction system comprising the extraction separation kettle, and an extraction method for low-temperature extraction of biological effective components using the extraction system. Background Art

[0002] When the pressure and temperature of the fluid exceed the values ​​corresponding to its critical point, the fluid enters a supercritical state. At this time, the interaction between the fluid molecules is between that of liquid and gas molecules. The fluid will simultaneously exhibit high density, good solubility and fluidity similar to liquids, as well as low viscosity and good diffusivity similar to gases, and can be used as an ideal extractant. At present, more than 90% of supercritical extraction processes are carried out using carbon dioxide, mainly because carbon dioxide has a low critical pressure and temperature, and has the advantages of being non-toxic, non-flammable, low cost, high purity, easy to diffuse, and low viscosity.

[0003] At present, the supercritical extraction device widely used in actual production is realized by constructing a supercritical extraction cycle: during the extraction process, the fluid will pass through the extraction kettle, separator, filter and other components in turn to complete the extraction, separation and self-purification of the extract. Finally, the fluid will enter the cycle to restore the initial state and re-enter the extraction kettle for the next extraction. The supercritical extraction circulation device currently used mainly has the following problems: ① There are many components required for the extraction, separation and purification process, and the actual cycle occupies a large space; ② The traditional hollow belt extraction kettle has the problem of low space utilization in the kettle and the direct current structure is easy to form wall flow and reduce flow stability; ③ The components are complicated and the disassembly process is cumbersome. It is the existence of these problems that greatly limits the extraction efficiency in actual production. Summary of the invention

[0004] In order to overcome the problems of space and efficiency in current supercritical extraction, the present invention proposes a new supercritical extraction separation kettle structure, and constructs a supercritical carbon dioxide circulation extraction system based on it.

[0005] In the first aspect of the present invention, a supercritical extraction separation kettle is proposed, comprising a kettle body, a top cover, an annular extraction layer, an annular porous medium layer, and a cyclone separator, wherein the top of the kettle body is sealed and connected to the top cover, an extractant outlet is provided at the center of the top cover, an extraction product outlet is provided at the center of the bottom of the kettle body, and a plurality of supercritical fluid inlet holes are provided in the middle of the side wall of the kettle body; inside the kettle body, from outside to inside, there are an annular extraction layer, an annular porous medium layer, and a cyclone separator; the raw material to be extracted is placed in the annular extraction layer and extracted by the supercritical fluid; the mixed fluid after extraction is filtered through the annular porous medium layer and enters the cyclone separator; the cyclone separator has a hollow central axis, the top end of the central axis is connected to the extractant outlet, and under the centrifugal action of the cyclone separator, the liquid extraction product with a larger density flows out from the extraction product outlet at the bottom of the kettle body, and the gaseous extraction agent with a smaller density enters the central axis and is discharged from the extractant outlet at the top.

[0006] Furthermore, the top cover and the kettle body are preferably made of carbon steel. In one embodiment of the present invention, the inner diameter of the kettle body is 500mm, the wall thickness is 60mm, and the height of the kettle body is 500mm. The kettle body and the top cover are sealed by a rubber ring and fastened by a bolt and nut assembly to achieve sealing of the kettle body. A plurality of (e.g., 4) supercritical fluid inlet holes are symmetrically opened in the center of the side wall of the kettle body, and the aperture of the supercritical fluid inlet hole is, for example, 12mm. A guide vane with an annular spiral structure is provided on the central axis of the cyclone separator. Preferably, the opening direction of the supercritical fluid inlet hole is consistent with the spiral direction of the guide vane on the central axis of the cyclone separator. In one embodiment of the present invention, the aperture of the extraction product outlet opened at the bottom of the kettle body is 20mm; the aperture of the extractant discharge outlet arranged in the center of the top cover is 20mm.

[0007] Furthermore, the annular extraction layer is a cylindrical double-layer structure, with an annular cylindrical frame formed by inner and outer walls with holes, which plays a rigid support role, and the hole diameter is preferably 0.5-1mm; close to the inner side of the inner and outer walls is a metal filter screen, which plays the role of isolating materials, and the filter screen mesh number is preferably not less than 35 meshes; a plurality of arc-shaped guide plates are arranged in an annular space of a certain width surrounded by the metal filter screen, and their drainage direction is consistent with the direction of the supercritical fluid inlet hole, which is used to increase the flow path of the supercritical fluid through the raw material powder to be extracted to improve the extraction efficiency.

[0008] The supercritical extraction separation kettle of the present invention replaces the functions of the filter, separator and throttle valve in the traditional supercritical extraction circulation device through a single annular porous medium layer. In one embodiment of the present invention, the thickness of the annular porous medium layer is 50 mm, and porous ceramics can be selected as the medium material. The median pore size of the medium is required to be below 50 μm to achieve the filtering and purification effect of the porous medium layer on the mixed fluid after extraction. In addition, preferably, the open porosity of the annular porous medium layer is above 60%, and the specific surface area is above 2.7 m2 / g or above to ensure the smooth flow of the supercritical fluid, and achieve the effect of turbulent pressure reduction through the complex structure inside the porous medium, which is convenient for the separation of the extraction agent and the extraction product.

[0009] In the supercritical extraction separation kettle of the present invention, the cyclone separator adopts a vertical cylindrical structure, wherein a guide blade is provided on the axis, and the guide blade preferably adopts an annular spiral structure from bottom to top, the blade height is 20 to 40 mm, and the blade spacing is 40 to 50 mm; the outer wall of the cyclone separator is preferably an annular metal frame with holes, which is close to the inner wall of the annular porous medium layer to prevent wall flow, and a plurality of (such as 4) arc-shaped guide plates are connected to the outer wall of the cyclone separator, and the opening direction thereof is consistent with the spiral direction of the guide blade on the axis of the cyclone separator, so as to make full use of the internal space of the equipment to reduce the load of the cyclone part. In actual production, the density difference between the extractant and the extracted product is utilized. The liquid extracted product with higher density is rotated to the outer wall of the central axis of the cyclone separator through centrifugal action, flows downward along the guide vanes due to gravity, is discharged through the extracted product outlet and stored in related containers, while the gaseous extractant with lower density is continuously drawn into the lower part of the cyclone separator, passes through the hollow central axis from the bottom of the central axis, and is finally discharged from the extraction separation kettle from the extractant outlet above the top cover of the kettle body.

[0010] In the supercritical extraction separation kettle of the present invention, preferably, arc guide plates are provided in the annular extraction layer and the cyclone separator, and the supercritical fluid entering from the supercritical fluid inlet hole is guided by the arc guide plates and guided in the annular extraction layer and the cyclone separator in turn to ensure smooth flow of the supercritical fluid in the extraction separation kettle.

[0011] In the second aspect of the present invention, a supercritical carbon dioxide circulation extraction system is constructed using the above-mentioned supercritical extraction separation kettle, and a method for low-temperature extraction of plant or microbial active substances is proposed.

[0012] The supercritical carbon dioxide circulation extraction system provided by the present invention comprises a supply tank, a heater, an infusion pump, a precooler, a supercritical extraction separation kettle, a cooler and pipelines connecting them, wherein the supply tank is used to store carbon dioxide liquid, the carbon dioxide liquid output from the supply tank is heated by the heater to be a supercritical carbon dioxide fluid, the supercritical carbon dioxide fluid enters the precooler for precooling under the action of the infusion pump, and then enters the supercritical extraction separation kettle to extract active ingredients from the material to be extracted in the kettle, the extraction product flows out from the bottom of the kettle body and is collected, and the separated supercritical carbon dioxide fluid is discharged from the top of the kettle body, and is circulated back to the supply tank after being cooled and liquefied by the cooler.

[0013] Furthermore, pressure sensors are provided on the pipeline from the heater to the infusion pump, the pipeline from the precooler to the supercritical extraction separation kettle, and the pipeline from the cooler to the supply tank to monitor the pressure of the fluid in each pipeline. A tachometer is provided on the pipeline from the infusion pump to the precooler to monitor the flow rate of the supercritical carbon dioxide fluid.

[0014] Furthermore, a throttle valve is provided on the pipeline from the precooler to the supercritical extraction and separation kettle to control the flow rate of the supercritical carbon dioxide entering the supercritical extraction and separation kettle; a throttle valve is also provided on the pipeline connecting the extractant outlet of the supercritical extraction and separation kettle and the cooler to control the flow rate of the discharged supercritical carbon dioxide fluid; and a throttle valve is also provided on the extraction product outflow pipeline at the bottom of the supercritical extraction and separation kettle.

[0015] In the above-mentioned supercritical carbon dioxide circulation extraction system, the carbon dioxide liquid stored in the supply tank is output to the heater, heated by the heater to the temperature and pressure required for extraction (50°C, 10-11MPa) to obtain a supercritical carbon dioxide fluid, and then enters the precooler for precooling under the action of an infusion pump, and the state of the supercritical carbon dioxide fluid at the outlet of the precooler is controlled to be 43.5-45.2°C and 10.0-10.5MPa, and is sent to a supercritical extraction and separation kettle for active ingredient extraction; under the action of a cyclone separator in the extraction and separation kettle, the extraction product flows out from the bottom of the kettle, and the separated supercritical carbon dioxide fluid is discharged from the top of the kettle, enters a cooler for cooling and liquefaction, and is stored back in the supply tank after reaching the required state (-20°C, 2.16MPa).

[0016] The workflow of low-temperature extraction of active components of biological materials using the above-mentioned supercritical carbon dioxide circulation extraction system is as follows:

[0017] 1) placing the pretreated powders of animals, plants, microorganisms or other biological materials to be extracted into the annular extraction layer in the extraction and separation kettle, and closing the top cover of the extraction and separation kettle;

[0018] 2) Turn on the cooler, heater and precooler, start the infusion pump, and the carbon dioxide liquid output from the supply tank is first heated to the temperature and pressure required by the supercritical fluid (50°C, 10-11MPa) by the heater, and then enters the precooler through the infusion pump for precooling, and the supercritical carbon dioxide fluid is controlled to the required state (43.5-45.2°C, 10.0-10.5MPa), and is continuously input into the extraction separation kettle for extraction;

[0019] 3) The supercritical carbon dioxide fluid separated from the cyclone separator in the extraction separation kettle is cooled and liquefied by a cooler, and after reaching the required state (-20°C, 2.16MPa), it is stored back in the supply tank;

[0020] 4) Continuously output carbon dioxide liquid from the supply tank, and repeat steps 2) and 3) to perform an extraction cycle until the desired extraction product is obtained.

[0021] In the above step 2), the carbon dioxide liquid is first heated to the temperature and pressure required by the supercritical fluid (50°C, 10-11 MPa) by a heater, and then pumped into the precooler for precooling by an infusion pump to avoid the "cavitation phenomenon" that causes a surge in pressure at the inlet of the extraction and separation kettle. The supercritical fluid state at the outlet of the precooler is controlled to be 43.5-45.2°C, 10.0-10.5 MPa to obtain higher extraction purity and extraction efficiency.

[0022] Preferably, in the above step 2), a tachometer is provided at the outlet of the infusion pump, and the power of the infusion pump is adjusted to control the reading of the tachometer to be within the range of 2 to 4 m / s.

[0023] The advantages of the present invention are:

[0024] 1) Compared with the bottom-up extractant input mode in the conventional extraction kettle, the annular layered structure of the extraction and separation kettle of the present invention enables the extractant to complete the extraction in the form of an inward rotation flow, thereby increasing the contact area between the extractant and the extractant during the flow process, thereby greatly improving the extraction yield;

[0025] 2) The annular layered structure design of the extraction and separation kettle of the present invention increases the space utilization rate inside the extraction kettle, avoids the common wall flow problem in the supercritical extraction process, and at the same time, by designing the direction of the air inlet and setting the arc-shaped guide plate, the flow field inside the extraction and separation kettle is made more uniform and stable;

[0026] 3) The present invention realizes the three functions of extraction, pressure reduction and separation and purification through one extraction and separation kettle, while the traditional cycle needs to set up three components separately to realize these functions. Compared with the traditional cycle, the equipment space is saved and the construction cost of the cycle is reduced;

[0027] 4) The unique combination of supercritical carbon dioxide extraction temperature and pressure, as well as the unique extraction and separation kettle structure design, achieves high-quality and efficient extraction of active ingredients from plants, animals and microorganisms;

[0028] 5) By constructing an extraction cycle, the carbon dioxide extractant can be reused, which greatly improves the extraction capacity (the extraction efficiency is increased by about 35%); BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the composition of a supercritical carbon dioxide circulation extraction system according to an embodiment of the present invention;

[0030] Figure 2 A longitudinal sectional view (front view) of an extraction separation kettle in an embodiment of the present invention;

[0031] Figure 3 A transverse cross-sectional view (top view) of an extraction separation kettle in an embodiment of the present invention;

[0032] In the figure: 1 is an extraction separation kettle, 2 is a first throttle valve, 3 is a second throttle valve, 4 is a cooler, 51 is a first pressure sensor, 52 is a second pressure sensor, 53 is a third pressure sensor, 6 is a supply tank, 7 is a heater, 8 is an infusion pump, 9 is a tachometer, 10 is a precooler, 11 is a third throttle valve, 1-1 is a top cover, 1-2 is a kettle body, 1-3 is an annular extraction layer, 1-4 is an annular porous medium layer, 1-5 is a cyclone Separator, 1-6 is a bolt and nut assembly, 1-1-1 is an extractant outlet, 1-2-1 is a supercritical fluid air inlet, 1-2-2 is an extraction product outlet, 1-3-1 is an annular cylindrical frame, 1-3-2 is an arc-shaped guide plate, 1-3-3 is a metal filter, 1-5-1 is an outer wall of a cyclone separator, 1-5-2 is an arc-shaped guide plate of a cyclone separator, 1-5-3 is a central axis of a cyclone separator, and 1-5-4 is a guide vane. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0034] like Figure 1As shown, the supercritical carbon dioxide circulation extraction system includes: an extraction separation kettle 1, a cooler 4, a supply tank 6, a heater 7, an infusion pump 8, and a precooler 10. The carbon dioxide liquid stored in the supply tank 6 is output to the heater 7, and is heated to the temperature and pressure (50°C, 10-11MPa) required for extraction by the heater 7 to obtain a supercritical carbon dioxide fluid; under the action of the infusion pump 8, the supercritical carbon dioxide fluid enters the precooler 10 for precooling, and the state of the supercritical carbon dioxide fluid at the outlet of the precooler 10 is controlled to be 43.5-45.2°C and 10.0-10.5MPa; the supercritical carbon dioxide fluid enters from the side of the extraction separation kettle 1 through a pipeline provided with a third throttle valve 11, and the active components of the material in the kettle are extracted; under the action of the cyclone separator in the extraction separation kettle 1, the extraction product flows out from the bottom of the extraction separation kettle 1, and a first throttle valve 2 is provided on the outflow pipeline to control the flow rate; and the separated supercritical carbon dioxide fluid is discharged from the top of the extraction separation kettle 1, and after the pressure is reduced by the second throttle valve 3, it enters the cooler 4 for cooling and liquefaction, and is stored back in the supply tank 6 after reaching the required state (-20°C, 2.16MPa). A first pressure sensor 51 is provided on the pipeline from the cooler 4 to the supply tank 6, a second pressure sensor 52 is provided on the pipeline from the heater 7 to the infusion pump 8, and a third pressure sensor 53 is provided on the pipeline from the precooler 10 to the extraction separation kettle 1, which are used to monitor the pressure of the fluid in each pipeline. The power of the infusion pump 8 is monitored by a tachometer 9 provided on the pipeline between the infusion pump 8 and the precooler 10.

[0035] The structure of the extraction separation kettle 1 in the above extraction system is as follows: Figure 2 and Figure 3 As shown, it includes a top cover 1-1, a kettle body 1-2, an annular extraction layer 1-3, an annular porous medium layer 1-4, and a cyclone separator 1-5, wherein the annular extraction layer 1-3, the annular porous medium layer 1-4, and the cyclone separator 1-5 are sequentially sleeved in the kettle body 1-2 from the outside to the inside; the annular extraction layer 1-3 is surrounded by an annular cylindrical frame 1-3-1 with holes on the inner and outer walls and a metal filter 1-3-3 close to the inner sides of the two walls to form a ring with a certain width. A space is formed in which four arc-shaped guide plates 1-3-2 are arranged at equal intervals; an extractant outlet 1-1-1 is arranged in the center of the top cover 1-1, and an extraction product outlet 1-2-2 is opened at the bottom of the kettle body 1-2; a related container can be connected below the extraction product outlet 1-2-2 to collect the extraction product; four supercritical fluid inlet holes 1-2-1 are arranged on the side wall of the kettle body 1-2, which respectively correspond to the positions of the four arc-shaped guide plates 1-3-2 in the annular extraction layer 1-3.

[0036] The top cover 1-1 and the kettle body 1-2 are made of Q245R carbon steel. The inner diameter of the kettle body 1-2 is 500mm, the wall thickness is 60mm, and the height of the kettle body is 500mm. The kettle body 1-2 and the top cover 1-1 are sealed by a polyurethane rubber ring and are fastened by a bolt and nut assembly 1-6 to achieve sealing of the kettle body. Four supercritical fluid inlet holes 1-2-1 are opened in the center of the side wall of the kettle body 1-2. The aperture of the supercritical fluid inlet hole 1-2-1 is 12mm, and its opening direction is consistent with the inner rotation direction of the cyclone separator center axis 1-5-3 (i.e., the spiral direction of the guide vane 1-5-4). The supercritical fluid entering from the supercritical fluid inlet hole 1-2-1 is drained by the arc guide plates 1-3-2 and 1-5-2 in the annular extraction layer 1-3 and the cyclone separator 1-5 in turn to ensure smooth flow of the supercritical fluid in the extraction separation kettle. The aperture of the extraction product outlet 1-2-2 opened at the bottom of the kettle body 1-2 is 20 mm; the aperture of the extraction agent outlet 1-1-1 set in the center of the top cover 1-1 is 20 mm.

[0037] Different from the traditional cylindrical extraction frame, the present invention adopts an annular extraction layer structure. The annular extraction layer 1-3 adopts a double-layer structure, and the inner layer width is 50mm (i.e., the radial distance between the outer wall and the inner wall of the perforated annular cylinder). The metal filter 1-3-3 located on the inner side of the inner and outer walls of the annular cylindrical frame 1-3-1 plays the role of isolating materials, and the number of filter meshes is not less than 35; the perforated annular cylinders on the inner and outer walls play the role of rigid support, and the hole diameter is 0.5 to 1mm; the inlet flow direction of the arc-shaped guide plate 1-3-2 provided in the annular extraction layer 1-3 is consistent with the direction of the supercritical fluid inlet hole 1-2-1, which is used to increase the flow path of the supercritical fluid through the raw material powder to be extracted to improve the extraction efficiency.

[0038] The present invention replaces the functions of the filter, separator and throttle valve in the traditional supercritical extraction cycle through a single annular porous medium layer 1-4. The annular porous medium layer 1-4 has a thickness of 50 mm, and porous ceramics can be selected as the medium material. The median pore size of the medium is required to be below 50 μm, so as to achieve the filtering and purification effect of the porous medium layer on the mixed fluid after extraction. In addition, the open porosity of the annular porous medium layer 1-4 is required to be above 60%, and the specific surface area is required to be above 2.7 m 2 / g or above to ensure the smooth flow of the supercritical fluid, and achieve the effect of turbulent pressure reduction through the complex structure inside the porous medium, which is convenient for the separation of the extraction agent and the extraction product.

[0039] The cyclone separator 1-5 adopts a vertical cylindrical structure. The outer wall 1-5-1 of the cyclone separator is a ring-shaped metal frame with holes, which is close to the inner wall of the porous medium layer 1-4 to prevent wall flow. Four equally spaced arc guide plates 1-5-2 are connected to the outer wall 1-5-1 of the cyclone separator. The opening direction is consistent with the spiral direction of the guide blade 1-5-4 on the central axis 1-5-3 of the cyclone separator, making full use of the internal space of the equipment to reduce the load of the cyclone part. The guide blade 1-5-4 adopts a bottom-up annular spiral structure, the blade height is 20-40mm, and the blade spacing is 40-50m m; the central axis 1-5-3 of the cyclone separator is a hollow structure. In actual production, the density difference between the extractant and the extracted product is utilized to centrifugally rotate the liquid extracted product with higher density to the outer wall of the central axis 1-5-3 of the cyclone separator, and flows downward along the guide blade 1-5-4 due to gravity, and is discharged through the extracted product outlet 1-2-2 and stored in a related container, while the gaseous extractant with lower density is continuously drawn into the lower part of the cyclone separator, passes through the hollow central axis from below the central axis 1-5-3 of the cyclone separator, and is finally discharged from the extraction separation kettle from the outlet 1-1-1 above the kettle body top cover 1-1.

[0040] The supercritical carbon dioxide circulation extraction system constructed by the extraction and separation kettle is used to extract the effective biological components in the herbal plants at low temperature.

[0041] Taking mugwort as an example, the following describes the extraction steps of herbal plant extracts:

[0042] 1) taking an appropriate amount of dry wormwood and placing it in a ball mill, grinding it at a low speed for 3 hours under cooling conditions, controlling the temperature of the grinding process not to exceed 35° C., and the particle size of the wormwood powder after grinding is 0.5-0.7 mm;

[0043] 2) placing the ground wormwood powder in the annular extraction layer 1-3 of the extraction and separation kettle 1, closing the top cover 1-1 of the extraction and separation kettle, tightening the sealing nut, and starting the supercritical carbon dioxide extraction cycle;

[0044] 3) adjusting the power of the infusion pump 8, controlling the flow rate of the extractant in the supercritical carbon dioxide extraction cycle to 2-4 m / s, controlling the supercritical carbon dioxide state input into the extraction and separation kettle 1 to 43.5-45.2° C., 10.0-10.5 MPa through the heater 7 and the precooler 10, and controlling the extraction time of the wormwood powder to 75-87 minutes (no more than 90 minutes);

[0045] 4) After the extraction is completed, the infusion pump 8 is turned off, the second throttle valve 3 and the third throttle valve 11 are closed, the first throttle valve 2 is opened, the liquid in the collector at the bottom of the extraction and separation kettle 1 is taken out, and the mixture is allowed to stand for 10 minutes. After the residual carbon dioxide is vaporized and separated, the desired liquid and oily wormwood extract is obtained.

[0046] The present invention is not limited to the above preferred embodiments. Those skilled in the art should understand that various changes, substitutions and modifications are possible based on the shapes and structures described in the embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention should not be limited to the contents disclosed in the drawings and embodiments, and the scope of protection claimed by the present invention shall be subject to the scope defined in the claims.

Claims

1. A supercritical extraction separation kettle, characterized in that: The invention comprises a kettle body, a top cover, an annular extraction layer, an annular porous medium layer, and a cyclone separator, wherein the top of the kettle body is sealedly connected to the top cover, an extractant outlet is arranged at the center of the top cover, an extraction product outlet is arranged at the center of the bottom of the kettle body, and a plurality of supercritical fluid inlet holes are opened in the middle of the side wall of the kettle body; in the kettle body, from the outside to the inside are the annular extraction layer, the annular porous medium layer, and the cyclone separator; the annular extraction layer is a cylindrical double-layer structure, and an annular cylindrical frame with inner and outer walls with holes is formed to play a rigid supporting role, and a metal filter screen is arranged closely to the inner side of the inner and outer walls to play the role of isolating materials; a plurality of arc-shaped guide plates are arranged in an annular space of a certain width surrounded by the metal filter screen, and the guide direction thereof is consistent with the direction of the supercritical fluid inlet hole; the cyclone separator is a vertical cylindrical structure, and a bottom-up guide plate is arranged on the shaft The guide vanes on the annular spiral structure, the opening direction of the supercritical fluid inlet hole is consistent with the spiral direction of the guide vanes on the central axis of the cyclone separator; the outer wall of the cyclone separator is an annular metal frame with holes, which is close to the annular porous medium layer, and a plurality of arc guide plates are connected to the inner wall of the outer wall, and the opening direction of the arc guide plates is consistent with the spiral direction of the guide vanes; the raw material to be extracted is placed in the annular extraction layer and extracted by the supercritical fluid; the extracted mixed fluid is filtered through the annular porous medium layer and then enters the cyclone separator; the cyclone separator has a hollow central axis, and the top end of the central axis is connected to the extractant outlet. Under the centrifugal action of the cyclone separator, the liquid extraction product with higher density flows out from the extraction product outlet at the bottom of the kettle body, and the gaseous extraction agent with lower density enters the central axis and is discharged from the extractant outlet at the top.

2. The supercritical extraction separation kettle according to claim 1, characterized in that: The side wall of the kettle body is provided with four supercritical fluid inlet holes with equal spacing, and correspondingly, four arc-shaped guide plates with equal spacing are arranged in the annular extraction layer.

3. The supercritical extraction separation kettle according to claim 1, characterized in that: The aperture of the annular cylindrical frame of the annular extraction layer is 0.5-1 mm, and the mesh number of the metal filter is not less than 35 meshes; the open porosity of the annular porous medium layer is above 60%, and the specific surface area is 2.7 m 2 / g or above, and the median pore size is below 50 μm.

4. The supercritical extraction separation kettle according to claim 1, characterized in that: The annular porous medium layer is porous ceramic.

5. A supercritical carbon dioxide circulation extraction system, comprising a supply tank, a heater, an infusion pump, a precooler, a supercritical extraction separation kettle, a cooler and pipelines connecting them, wherein the supercritical extraction separation kettle is as described in any one of claims 1 to 4, the supply tank is used to store carbon dioxide liquid, the carbon dioxide liquid output from the supply tank is heated to a supercritical carbon dioxide fluid by the heater, the supercritical carbon dioxide fluid enters the precooler for precooling under the action of the infusion pump, and then enters the supercritical extraction separation kettle to extract active ingredients from the material to be extracted in the kettle, the extraction product flows out from the bottom of the kettle body of the supercritical extraction separation kettle and is collected, and the separated supercritical carbon dioxide fluid is discharged from the top of the kettle body, and is circulated back to the supply tank after being cooled and liquefied by the cooler.

6. The supercritical carbon dioxide circulation extraction system according to claim 5, characterized in that: Pressure sensors are respectively provided on the pipeline from the heater to the infusion pump, on the pipeline from the precooler to the supercritical extraction and separation kettle, and on the pipeline from the cooler to the supply tank; a tachometer is provided on the pipeline from the infusion pump to the precooler; throttle valves are respectively provided on the pipeline from the precooler to the supercritical extraction and separation kettle, on the pipeline connecting the extractant outlet of the supercritical extraction and separation kettle and the cooler, and on the extraction product outflow pipeline at the bottom of the supercritical extraction and separation kettle.

7. A method for low-temperature extraction of active ingredients from biological materials, using the supercritical carbon dioxide circulation extraction system of claim 5 to perform the following operations: 1) placing the biological material powder to be extracted in the annular extraction layer in the supercritical extraction separation kettle, and closing the top cover of the supercritical extraction separation kettle; 2) Turn on the cooler, heater and precooler, start the infusion pump, and the carbon dioxide liquid output from the supply tank is first heated to the temperature and pressure required by the supercritical fluid by the heater, and then enters the precooler for precooling through the infusion pump. The supercritical carbon dioxide fluid is controlled to the required state and continuously input into the supercritical extraction separation kettle to extract the biomaterial powder; 3) The supercritical carbon dioxide fluid separated from the cyclone separator in the supercritical extraction separation kettle is cooled and liquefied by the cooler and then stored back in the supply tank; 4) Continuously output carbon dioxide liquid from the supply tank and repeat steps 2) and 3) to perform an extraction cycle until the desired extraction product is obtained.

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