Tea saponin purification process and application

Abstract

The application belongs to the technical field of tea saponin purification, and particularly relates to a tea saponin purification process and application, which comprises flocculation and separation of tea saponin stock solution, extraction and separation of the separated tea saponin solution, addition of an alkaline precipitant to the tea saponin solution after defatting and desolventizing, phase inversion precipitation and filtration separation under alkaline conditions, separation of non-precipitant, acetone extraction, washing and filtration of the alkaline precipitant, extraction and washing of the acetone-dissolved substance, drying of the washed and separated saponin precipitant in a drying machine to obtain tea saponin powder, addition of a releasing agent to the tea saponin powder, analysis and release, filtration, removal of solid substances after analysis, removal of small molecules and other macromolecular substances in the obtained tea saponin solution by a membrane separation technology, and direct proportioning of the obtained tea saponin solution as a raw material into cosmetics and washing products, or concentration and spray drying to obtain tea saponin powder.

Description

Technical Field

[0001] The invention belongs to the technical field of tea saponin purification, and in particular relates to a tea saponin purification process and application. Background Art

[0002] Extraction and purification are technically challenging aspects of tea saponin preparation and have been a hot topic of research in recent years. my country boasts abundant tea seed resources and enormous potential for utilization, making the development of tea saponin applications both highly practical and promising. By employing appropriate extraction and purification processes, tea saponin can be obtained in high yield and high purity. This extracted and purified tea saponin can be used in agriculture and other fields, transforming oil-tea camellia cake into valuable resources with excellent economic value. Furthermore, as a natural product, tea saponin has no adverse effects on plant growth, is easily degraded in the environment, is non-toxic to humans and animals, and exhibits excellent environmental compatibility. These characteristics of tea saponin lay a solid foundation for its broad application prospects. Efficient separation and purification of high-purity tea saponin is a pressing issue awaiting resolution in the industrialization of oil-tea camellia. Summary of the Invention

[0003] The purpose of the present invention is to provide a tea saponin purification process and application. Through this system and process, purification of crude tea saponin from 35% to high-purity tea saponin 95% can be achieved, and better and higher-quality tea saponin products can be obtained. The device and process are suitable for the tea saponin (similar substances such as isoflavones, pigments, etc.) purification industry, and can produce tea saponin products of various concentrations according to the purity requirements of the products.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A tea saponin purification process comprises the following steps:

[0006] S1. Flocculation and impurity removal of crude tea saponin: After removing impurities from a crude tea saponin stock solution with a concentration of 25-40% using a bag filter, the crude tea saponin filtrate is mixed with a flocculant in a mixer and then sent to a flocculation reaction tank for reaction at 40-50°C for 1 hour. The colloid, protein and some pigments in the raw material solution are flocculated and adsorbed. 3-5% of the flocs are then separated through separation, and the flocs are then separated to obtain a crude tea saponin clear solution.

[0007] S2. Extraction and degreasing: The crude tea saponin liquid and hexane are mixed in a mixer at a mass ratio of 1:0.4 and then fed into an extraction tank. After extraction at 50-55°C for 0.5h, the solvent dissolves 3-5% of the oil and other fat-soluble substances in the liquid, separating the heavy phase of the degreased saponin liquid and the light phase of the mixed oil. Both phases are evaporated in an evaporator to recover the solvent;

[0008] S3. Tea Saponin Phase Inversion Precipitation: The defatted saponin solution is mixed with 2-3% CaO, a phase inversion precipitant, in a premixing tank. The mixture is then placed in a phase inversion precipitation tank and reacted at 40-50°C for 2-3 hours, with a conversion rate of 85-90%. The phase inversion mixture is filtered through a horizontal feed filter separator to separate the precipitated solid saponin salts for the next stage. The filtered mixture is then membrane separated, concentrated, and spray dried to obtain the polysaccharide solution product.

[0009] S4. Multi-stage extraction and separation: The solid saponin salt and acetone are fed into a multi-stage countercurrent extraction and separation system in a ratio of 1:1 and extracted at 60-70°C for 0.5-1h. The countercurrent extraction and washing are repeated three times. The precipitated solid saponin salt first enters the first-stage horizontal extractor and then enters the spiral drum separation screen to separate the solid matter and the mixed liquid. The mixed liquid is mixed with the solvent liquid from the second-stage horizontal extractor and then re-enters the first-stage extractor through a circulation pump. The saponin salt solids enter the second-stage horizontal extractor, and the cycle repeats. The final solvent extraction mixed liquid exits the first-stage horizontal extractor and passes through a filter into the extraction liquid mixing tank. The horizontal extractor is kept warm by a jacket. After extraction and washing, The acetone-soluble substances such as polysaccharides and pigments remaining in the precipitated solid saponin salt can be extracted into the extractant solution, and the extracted mixed liquid is then desolvated. The polysaccharides and pigments enter the storage tank, and the solvent is recovered and recycled. The saponin salt is desolvated in a dryer, and the solvent is condensed and recovered and recycled. The saponin salt enters the next stage. This process uses a spiral drum separation screen to separate the solid and liquid. Compared with the natural drainage of the traditional extractor, the moisture content of the solid is lower. At the same time, fresh solvent enters from the third-stage extractant and is countercurrently extracted and washed with the solid saponin salt before entering the secondary extractor. The solvent concentration decreases successively. Through multi-stage countercurrent extraction of solvents with different concentration gradients, the separated saponin salt has a higher purity.

[0010] S5. Desorption and filtration: Add 5-6% ammonium bicarbonate solution, a desorption release agent, to the saponin salt, then mix in a premix tank. After mixing, enter the desorption tank and react at 40-50°C for 0.5-1h. The desorption release rate of the saponin salt is 80-90%. After filtering the mixture, calcium carbonate precipitate is obtained as a by-product, and the tea saponin solution enters the next stage;

[0011] S6. Activated carbon adsorption: Add 1-1.5% activated carbon to the tea saponin solution and mix in a premixing tank. After mixing, place the mixture in an adsorption reaction tank and react at 80-90℃ for 0.5-1h. After the reaction, heavy metal ions and other harmful substances are adsorbed into the activated carbon. After filtration, a high-purity tea saponin solution is obtained.

[0012] S7. Membrane separation: The high-purity tea saponin solution is subjected to membrane separation to separate the small molecules (salts) and other large molecules (molecular weight greater than tea saponin) and non-tea saponin components in the solution to obtain a high-purity tea saponin solution, which is then concentrated and spray-dried to obtain tea saponin powder with a purity of 95%.

[0013] Furthermore, the flocculant is a chitosan solution with a mass fraction of 1% prepared with 1% glacial acetic acid as a solvent, and the amount of the flocculant added is 20% of the mass of the crude tea saponin filtrate. The mass fraction of the ammonium bicarbonate solution in the analytical filtration is 18%.

[0014] Furthermore, the multi-stage countercurrent extraction and separation system includes three stages of horizontal extractors connected end to end, and a spiral drum separation screen is provided between adjacent horizontal extractors, that is, after the discharge port of the upper-stage horizontal extractor enters the spiral drum separation screen for solid-liquid separation, the solid enters the lower-stage horizontal extractor for further extraction, and the liquid is refluxed to the upper-stage horizontal extractor through a pump for continued use as a solvent. The discharge port of the last-stage horizontal extractor is connected to the inlet of the horizontal spiral filter separator, and the solvent of the last-stage horizontal extractor comes from fresh solvent.

[0015] Furthermore, the horizontal extractor includes a tubular shell, with end plates at both ends of the tubular shell, and also includes multiple sections of shaft tubes located in the center of the shell and running through the two end plates, with the end plates connected end to end. Adjacent shaft tubes are connected by hanging supports, and the shaft tubes and the end plates are rotatably connected by shaft heads and bearings inserted into the shaft tubes. The shaft heads are driven by a motor reducer, and a coupling is provided between the motor reducer and the shaft head. Each section of the shaft tube is provided with a cage-shaped stirring mixer formed by welding multiple horizontal flat steels through spokes vertically mounted on the shaft tube. Each section of the cage-shaped stirring mixer is provided with a spiral belt along its length. The inner side of the spiral belt is welded to the outer edge of the flat steel, and the outer edge of the spiral belt is in point contact with the shell. Multiple sections of spiral belts are connected to form a continuous spiral belt-type pushing structure.

[0016] Furthermore, the cage-shaped stirring mixer is connected into a cage shape by a plurality of first spokes vertically mounted on the shaft tube and a plurality of flat steels evenly welded to the outer circumference of the spokes, and spiral bands are welded in sequence in a spiral shape on each flat steel on the outer circumference of the cage along the length direction; a mechanical seal and a bearing group are provided on the outer side of the left end plate of the extractor shell, that is, the outer side of the front end of the shaft tube, and a sealing cover is provided on the outer side of the right end plate, that is, the outer side of the tail of the shaft tube, and a feed port and a discharge port are provided at both ends of the extractor shell.

[0017] Furthermore, the spiral drum separation screen includes a frame located at the bottom, a first motor reducer arranged at the left end of the frame, the first motor reducer drives the spiral feeding mechanism to rotate through the first main shaft at the output end, and also includes a second motor reducer located at the right end of the frame, the second motor reducer drives the second spoke to rotate through the bearing group base sleeved on the second main shaft at the output end, the left side of the second spoke is fixedly connected to the cylindrical drum separation screen through multiple connecting rods, and also includes a cylinder, one end of the cylinder is connected to the first main shaft through a bearing, and the other end of the cylinder is connected to the second main shaft through a bearing, a feed port is provided at the top of the left end of the cylinder, a discharge port is provided at the bottom of the right end of the cylinder, and a liquid collecting hopper and a liquid outlet are also provided at the front end of the discharge port at the bottom of the cylinder.

[0018] Furthermore, the spiral feeding mechanism includes a small-diameter spiral conveying feeding blade and a large-diameter spiral conveying pushing blade, the cylinder includes a feeding section and a separation section, the inner diameter of the feeding section is smaller than the inner diameter of the drum separation screen, the feeding section is located outside the small-diameter spiral conveying feeding blade, the large-diameter spiral conveying pushing blade is located inside the drum separation screen, and the separation section is located outside the drum separation screen and the bearing group.

[0019] The invention discloses an application of a tea saponin solution prepared by a tea saponin purification process. The tea saponin solution can be used as a raw material to directly mix cosmetics and detergents.

[0020] The advantages of the present invention are:

[0021] 1. The process of the present invention can purify the concentration of crude tea saponin solution from 35% to 95%, which is higher than the effect achieved by general processing technology in the field, and the whole process is simple and low in cost;

[0022] 2. The multi-stage countercurrent extraction in the present invention can fully dissolve other impurities of crude tea saponin, which helps the subsequent purification. In addition, since the extractor is provided with a multi-section cage mixer and a spiral belt, the adjacent shaft tubes are fixed by hanging supports. The segmented hanging supports can ensure the stable operation of the equipment and adapt to the horizontal extractor with a long-axis ratio. The spiral belt is arranged on the outside of the flat steel and makes point contact with the inner wall of the shell, which can not only push the material forward, but also make the material deposited at the bottom turn upward. The solvent and the material can fully contact and extract, thereby effectively improving the extraction effect of the solvent on the material. The cage mixer is evenly distributed around the circumference. The flat steel used to connect the cage can effectively turn over the material settled at the bottom of the extractor, so that the material can further fully contact with the solvent.

[0023] 3. The spiral drum separation screen of the present invention is suitable for a variety of dry and wet separations of materials including but not limited to extracted materials, and can transport solid materials out during centrifugal separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the multi-stage extraction, separation and analytical filtration sections in the present invention.

[0025] Figure 2 yes Figure 1 Structural diagram of a medium horizontal extractor.

[0026] Figure 3 yes Figure 2 Cross-section of the BB.

[0027] Figure 4 yes Figure 1 Structural diagram of the spiral drum separation screen. DETAILED DESCRIPTION

[0028] As shown in the figure, a tea saponin purification process includes the following steps:

[0029] S1. Flocculation and impurity removal of crude tea saponin: After removing impurities from a crude tea saponin stock solution with a concentration of 25-40% using a bag filter, the crude tea saponin filtrate is mixed with a flocculant in a mixer and then fed into a flocculation reaction tank for reaction at 40-50°C for 1 hour. The colloid, protein, and some pigments in the raw material solution are flocculated and adsorbed. Then, 3-5% of the flocculants are separated by separation, and the flocculants are separated to obtain a crude tea saponin clear solution. The flocculant is a 1% chitosan solution prepared with 1% glacial acetic acid as a solvent, and the amount of flocculant added is 20% of the mass of the crude tea saponin filtrate;

[0030] S2. Extraction and degreasing: The crude tea saponin liquid and hexane are mixed in a mixer at a mass ratio of 1:0.4 and then fed into an extraction tank. After extraction at 50-55°C for 0.5h, the solvent dissolves 3-5% of the oil and other fat-soluble substances in the liquid, separating the heavy phase of the degreased saponin liquid and the light phase of the mixed oil. Both phases are evaporated in an evaporator to recover the solvent;

[0031] S3. Tea Saponin Phase Inversion Precipitation: The defatted saponin solution is mixed with 2-3% CaO, a phase inversion precipitant, in a premixing tank. The mixture is then transferred to a phase inversion precipitation tank and reacted at 40-50°C for 2-3 hours, with a conversion rate of 85-90%. The mixture is then filtered through a horizontal feed filter separator to separate the precipitated solid saponin salts for the next stage. The filtered mixture is then membrane separated, concentrated, and spray-dried to obtain the polysaccharide solution product.

[0032] S4. Multi-stage extraction and separation: The solid saponin salt and acetone are fed into a multi-stage countercurrent extraction and separation system in a ratio of 1:1 and extracted at 60-70°C for 0.5-1h. The countercurrent extraction and washing are repeated three times. The precipitated solid saponin salt first enters the first-stage horizontal extractor and then enters the spiral drum separation screen to separate the solid matter and the mixed liquid. The mixed liquid is mixed with the solvent liquid from the second-stage horizontal extractor and then re-enters the first-stage extractor through a circulation pump. The saponin salt solids enter the second-stage horizontal extractor, and the cycle repeats. The final solvent extraction mixed liquid exits the first-stage horizontal extractor and passes through a filter into the extraction liquid mixing tank. The horizontal extractor is kept warm by a jacket. After extraction and washing, The acetone-soluble substances such as polysaccharides and pigments remaining in the precipitated solid saponin salt can be extracted into the extractant solution, and the extracted mixed liquid is then desolvated. The polysaccharides and pigments enter the storage tank, and the solvent is recovered and recycled. The saponin salt is desolvated in a dryer, and the solvent is condensed and recovered and recycled. The saponin salt enters the next stage. This process uses a spiral drum separation screen to separate the solid and liquid. Compared with the natural drainage of the traditional extractor, the moisture content of the solid is lower. At the same time, fresh solvent enters from the third-stage extractant and is countercurrently extracted and washed with the solid saponin salt before entering the secondary extractor. The solvent concentration decreases successively. Through multi-stage countercurrent extraction of solvents with different concentration gradients, the separated saponin salt has a higher purity.

[0033] S5. Desorption filtration: Add 5-6% ammonium bicarbonate solution as a release agent to the saponin salt, wherein the mass fraction of the ammonium bicarbonate solution in the desorption filtration is 18%, and then mix in a premixing tank. After mixing, enter the desorption tank and react at 40-50 ° C for 0.5-1h. The saponin salt desorption release rate is 80-90%. After filtering the mixture, calcium carbonate precipitate is obtained as a by-product. The tea saponin solution enters the next stage;

[0034] S6. Activated carbon adsorption: Add 1-1.5% activated carbon to the tea saponin solution and mix in a premixing tank. After mixing, place the mixture in an adsorption reaction tank and react at 80-90℃ for 0.5-1h. After the reaction, heavy metal ions and other harmful substances are adsorbed into the activated carbon. After filtration, a high-purity tea saponin solution is obtained.

[0035] S7. Membrane separation: The high-purity tea saponin solution is subjected to membrane separation to separate the small molecules (salts) and other large molecules (molecular weight greater than tea saponin) and non-tea saponin components in the solution to obtain a high-purity tea saponin solution, which is then concentrated and spray-dried to obtain tea saponin powder with a purity of 95%.

[0036] Furthermore, the multi-stage countercurrent extraction and separation system includes three stages of horizontal extractors connected end to end, and a spiral drum separation screen is provided between adjacent horizontal extractors, that is, after the discharge port of the upper-stage horizontal extractor enters the spiral drum separation screen for solid-liquid separation, the solid enters the lower-stage horizontal extractor for further extraction, and the liquid is refluxed to the upper-stage horizontal extractor through a pump to continue to be used as a solvent. The discharge port of the last-stage horizontal extractor is connected to the inlet of the horizontal spiral filter separator, and the solvent of the last-stage horizontal extractor comes from fresh solvent; the horizontal extractor 1 includes a tubular shell 11, and end plates 12 are provided at both ends of the tubular shell 11, and also includes a shell located The center of the body 11 passes through the multi-section shaft tube 17 connected end to end between the two end plates. The adjacent shaft tubes 17 are connected by hanging supports 18. Each hanging support 18 is composed of a fixed part located at the upper part and a hanging part located at the lower part. The hanging part includes a hanger located in the middle, a bearing located at the lower end of the hanger, an intermediate shaft in the bearing and a sleeve arranged outside the bearing. The sleeve intermediate shaft penetrates the ends of the shaft tubes 17 at the left and right ends and is fixed by bolts. The shaft tube 17 and the end plate 12 are rotatably connected to the bearing through the shaft head inserted into the shaft tube. The shaft head is driven by the motor reducer 13. A coupling 14 is provided between the motor reducer 13 and the shaft head. Each of the plurality of horizontal flat steels 116 is welded by a first spoke 115 mounted vertically on the shaft tube 17, and a cage-shaped stirring mixer is provided. The connection between the first spoke 115 and the flat steel 116 is further provided with a reinforcing rib 117. The outer periphery of each section of the cage-shaped mixing pusher is provided with a section of spiral belt 19 along its length direction. The connection between the flat steel and the spiral belt is also provided with a reinforcing rib 117. The inner side of each section of the spiral belt is welded to the outer edge of the flat steel, and the outer edge of the spiral belt is in point contact with the shell. Multiple sections of spiral belts are connected to form a continuous spiral belt pusher structure. The cage-shaped stirring mixer is connected by a plurality of first spokes 115 through flat steel 116 evenly distributed on its circumference. It is cage-shaped, with spiral strips welded on each strip of flat steel in sequence along the length direction, and multiple strips of flat steel are evenly welded to the outer circumference of the spoke; a mechanical seal 16 and a bearing group 15 are provided on the outside of the left end plate of the shell, that is, the front end of the shaft tube, and a sealing cover 110 is provided on the outside of the right end plate, that is, the outside of the tail of the shaft tube. A feed port 111 and a discharge port 112 are provided at both ends of the extractor shell respectively; a mixed liquid inlet 113 and a mixed liquid overflow port 114 are provided at both ends of the extractor shell respectively, and the liquid level height of the overflow port 114 is lower than the height of the extractor feed port 111, to ensure that when multiple extractors are used in series, the mixed liquid of the upper extractor will not flow through the air shutoff to the lower extractor.

[0037] Furthermore, the spiral drum separation screen 2 includes a frame at the bottom, a first motor reducer 21 arranged at the left end of the frame, the first motor reducer 21 drives the spiral feeding mechanism 212 to rotate through the first main shaft 213 at the output end, and also includes a second motor reducer 214 at the right end of the frame, the second motor reducer 214 is connected to the base of the bearing group 29 through the second main shaft at the output end to drive the second spoke 215 to rotate, the left side of the second spoke 215 is fixedly connected to the cylindrical drum separation screen 25 through a plurality of connecting rods, and also includes a cylinder, one end of the cylinder is connected to the first main shaft through a bearing The other end of the cylinder is connected to the second main shaft through a bearing. A feed port is provided at the top of the left end of the cylinder, a discharge port is provided at the bottom of the right end of the cylinder, and a liquid collecting hopper 27 and a liquid outlet are also provided at the front end of the discharge port at the bottom of the cylinder; the spiral feeding mechanism 212 includes a small-diameter spiral conveying feeding blade 24 and a large-diameter spiral conveying pushing blade 26, and the cylinder includes a feeding section 23 and a separation section 28. The inner diameter of the feeding section is smaller than the inner diameter of the drum separation screen 25. The feeding section 23 is located outside the small-diameter spiral conveying feeding blade 24, and the large-diameter spiral conveying pushing blade 26 is located inside the drum separation screen 25. The separation section 28 Located outside the drum separation screen 25 and the bearing group 29, the feeding section and the separation section are separately arranged and the inner diameter of the feeding section 23 is smaller than the inner diameter of the drum separation screen 25. The first main shaft 213 and the second main shaft are connected through the bearing group. The right end of the first main shaft is located at the inner ring of the bearing group 29. The second main shaft is connected to the bearing group base arranged outside the bearing group. The bearing group base is connected to the outer ring of the bearing group. This form can meet the strength requirements of the main shaft without affecting the operation form between each other. The drum separation screen 25 and the first main shaft 213 are movably connected through a plurality of second spokes 215. This setting can meet the support requirements of the drum separation screen. Strength, the large-diameter spiral conveying and pushing blades 26 are segmented blades, and adjacent large-diameter spiral conveying and pushing blades 26 are separated by spokes sleeved on the bearings, and the spokes are located on the outer ring of the bearings, and the inner ring of the bearings is fixedly connected to the first main shaft. The setting of the spokes can not only meet the realization of relative movement, but also meet the strength support; the feed port is located on the cylinder of the feeding section 23, and the liquid collecting hopper 27 and the discharge port are located at the bottom of the cylinder of the separation section 28; a plurality of flushing pipes 211 are provided on the top of the cylinder of the separation section 28 facing the drum separation screen 25, and the flushing pipes 211 are convenient for cleaning the drum separation screen 25 to avoid blockage.

[0038] The invention discloses an application of a tea saponin solution prepared by a tea saponin purification process. The tea saponin solution can be used as a raw material to directly mix cosmetics and detergents.

Claims

1. A tea saponin purification process, characterized in that: The following steps are involved: S1. Flocculation and impurity removal of crude tea saponin: After removing impurities from a crude tea saponin stock solution with a concentration of 25-40% using a bag filter, the crude tea saponin filtrate is mixed with a flocculant in a mixer and then fed into a flocculation reaction tank for reaction at 40-50°C for 1 hour. The flocculants are then separated to obtain a crude tea saponin clear solution; the flocculant is a 1% chitosan solution prepared with 1% glacial acetic acid as a solvent, and the amount of flocculant added is 20% of the mass of the crude tea saponin filtrate; S2. Extraction and degreasing: The crude tea saponin liquid and hexane are mixed in a mixer at a mass ratio of 1:0.4 and fed into an extraction tank. After extraction at 50-55 ° C for 0.5h, the heavy phase of the degreased saponin liquid and the light phase of the mixed oil are separated. The two are evaporated into the evaporator to recover the solvent; S3. Tea Saponin Phase Transfer Precipitation: The defatted saponin solution is mixed with 2-3% CaO as a phase transfer precipitant in a premixing tank. The mixture is then transferred to a phase transfer precipitation tank and reacted at 40-50°C for 2-3 hours. The mixture is then filtered through a horizontal feed filter separator to separate the precipitated solid saponin salts for the next stage. The filtered mixture is then membrane separated, concentrated, and spray-dried to obtain the polysaccharide solution product. S4. Multi-stage extraction and separation: solid saponin salt and acetone are sent to a multi-stage countercurrent extraction and separation system in a ratio of 1:1 and extracted at 60-70°C for 0.5-1h. The extracted mixed liquid is sent to an evaporator for desolventizing, and the solvent is recovered and recycled. The polysaccharide and pigment enter the storage tank, and the saponin salt is sent to a dryer for drying and desolventizing. The solvent is condensed and recovered, and the saponin salt enters the next stage; the multi-stage countercurrent extraction and separation system includes three stages of horizontal extractors connected end to end, and a spiral drum separation screen is provided between adjacent horizontal extractors, that is, after the discharge port of the upper horizontal extractor enters the spiral drum separation screen for solid-liquid separation, the solid enters the lower horizontal extractor for further extraction, and the liquid is refluxed to the upper horizontal extractor through a pump to continue to be used as a solvent. The discharge port of the last horizontal extractor is connected to the inlet of the horizontal spiral filter separator, and the solvent of the last horizontal extractor comes from fresh solvent; the horizontal extractor includes a tubular shell, both ends of the tubular shell are provided with end plates, and also includes a shell located in the center of the shell and passing through the two end plates. The shaft tubes are connected end to end, and the adjacent shaft tubes are connected by hanging supports. The shaft tubes and the end plates are connected by shaft heads inserted into the shaft tubes and the bearings. The shaft heads are driven by motor reducers, and a coupling is provided between the motor reducer and the shaft heads. Each section of the shaft tube is provided with a cage-shaped stirring mixer formed by welding multiple horizontal flat steels through spokes vertically mounted on the shaft tube. The outer periphery of each section of the cage-shaped stirring mixer is provided with a spiral belt along its length. The inner side of the spiral belt is welded to the outer edge of the flat steel, and the outer edge of the spiral belt is welded to the shell. The structure is point-contact, and multiple sections of spiral belts are connected to form a continuous spiral belt pusher structure. The cage-shaped stirring mixer is connected to form a cage shape by multiple first spokes mounted vertically on the shaft tube and multiple flat steels uniformly welded to the outer circumference of the spokes. Spiral belts are welded in sequence in a spiral shape along the length direction on each flat steel on the outer circumference of the cage. A mechanical seal and a bearing group are provided on the outer side of the left end plate of the extractor shell, i.e., the outer side of the front end of the shaft tube, and a sealing cover is provided on the outer side of the right end plate, i.e., the outer side of the rear end of the shaft tube. A feed port and a discharge port are provided at both ends of the extractor shell. S5. Desorption and filtration: Add 5-6% ammonium bicarbonate solution, a desorption release agent, to the saponin salt, then mix in a premix tank. After mixing, enter the desorption tank and react at 40-50°C for 0.5-1h. The mass fraction of ammonium bicarbonate solution in the desorption filtration is 18%. After filtering the mixture, calcium carbonate precipitate is obtained as a by-product, and the tea saponin solution enters the next stage; S6. Activated carbon adsorption: Add 1-1.5% activated carbon to the tea saponin solution in a premixing tank and mix. After mixing, place the mixture into an adsorption reaction tank and react at 80-90°C for 0.5-1h. Filter to obtain a high-purity tea saponin solution. S7. Membrane separation: The high-purity tea saponin solution is separated by membrane to obtain a high-purity tea saponin solution, which is then concentrated and spray-dried to obtain tea saponin powder with a purity of 95%.

2. The tea saponin purification process according to claim 1, wherein: The spiral drum separation screen includes a frame located at the bottom, a first motor reducer arranged at the left end of the frame, the first motor reducer drives the spiral feeding mechanism to rotate through the first main shaft at the output end, and also includes a second motor reducer located at the right end of the frame, the second motor reducer drives the second spoke to rotate through the bearing group base sleeved on the second main shaft at the output end, the left side of the second spoke is fixedly connected to the cylindrical drum separation screen through multiple connecting rods, and also includes a cylinder, one end of the cylinder is connected to the first main shaft through a bearing, and the other end of the cylinder is connected to the second main shaft through a bearing, a feed port is provided at the top of the left end of the cylinder, a discharge port is provided at the bottom of the right end of the cylinder, and a liquid collecting hopper and a liquid outlet are also provided at the front end of the discharge port at the bottom of the cylinder.

3. The tea saponin purification process according to claim 2, wherein: The spiral feeding mechanism includes a small-diameter spiral conveying feeding blade and a large-diameter spiral conveying pushing blade. The cylinder includes a feeding section and a separation section. The inner diameter of the feeding section is smaller than the inner diameter of the drum separation screen. The feeding section is located outside the small-diameter spiral conveying feeding blade, and the large-diameter spiral conveying pushing blade is located inside the drum separation screen. The separation section is located outside the drum separation screen and the bearing group.

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