CN118290606A - Method for extracting dendrobium candidum polysaccharide based on supercritical extraction method - Google Patents

Abstract

The invention relates to the technical field of dendrobium candidum polysaccharide extraction, in particular to a method for extracting dendrobium candidum polysaccharide based on a supercritical extraction method, which comprises the steps of converting carbon dioxide gas into supercritical fluid by adopting a phase change device, wherein the phase change device consists of a high-pressure circulating pump and a heater; the outside seal cover of pressurize jar is equipped with draws the jar, draws the bottom one side wall of jar and is provided with the booster pump, draws the middle part one side wall of jar and is provided with the unloading pump, is provided with the ball valve in the row material pipe. The invention is characterized in that the extraction tank and the pressure maintaining tank are arranged inside and outside, and then the booster pump is started to suck air between the extraction tank and the pressure maintaining tank and enter the pressure maintaining tank to boost the pressure to the pressure environment in the phase change device; the vacuum state is formed in the extraction tank, so that the temperature in the pressure maintaining tank is prevented from being lost and the pressure is prevented from being influenced; the extraction mode is simple and orderly, and the extraction cost is reduced.

Description

Method for extracting dendrobium candidum polysaccharide based on supercritical extraction method

Technical Field

The invention relates to the technical field of dendrobium candidum polysaccharide extraction, in particular to a method for extracting dendrobium candidum polysaccharide based on a supercritical extraction method.

Background

Supercritical fluids, which are a non-gaseous and non-liquid state of matter between gas and liquid, are only present when the temperature and pressure exceed critical points. The supercritical fluid is an ideal extractant because of the characteristics of high dissolution capacity, low viscosity, high diffusion coefficient and the like. Supercritical carbon dioxide is widely used because of its characteristics of non-toxicity, odorlessness, difficult explosion, etc.

The application number CN202010063193.0 discloses an extraction process of dendrobe polysaccharide and dendrobine in dendrobium candidum, which comprises the following steps: (1) cleaning, drying and crushing dendrobium; (2) Extracting herba Dendrobii powder with supercritical CO ₂ to obtain extract A; (3) Extracting the extract A, concentrating under reduced pressure, and drying to obtain dendrobine; (4) Soaking herba Dendrobii residue in water, centrifuging, evaporating supernatant, and concentrating to obtain extract B; (5) Filtering the extractive solution B, retaining the precipitate, and filtering to collect filtrate; and freeze-drying the filtrate to obtain the dendrobium polysaccharide.

In practical operation, parameters such as extraction temperature, pressure, fluid flow and the like need to be optimized to obtain the best extraction effect. During extraction, a sealed tank is required to store and extract, a plurality of iron tanks are commonly used in the prior art for storing dendrobe and decompressing and cooling extract liquid to separate out polysaccharide, so that a plurality of groups of pressure-maintaining and heat-preserving equipment are required to be arranged, and the use and maintenance cost is high; in addition, the extraction liquid is transported through a pipeline, so that the supercritical fluid is easy to lose pressure and temperature, and the supercritical fluid is phase-changed in advance, which is unfavorable for thoroughly collecting polysaccharide liquid and carbon dioxide gas.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a method for extracting dendrobium candidum polysaccharide based on a supercritical extraction method so as to solve the problems in the background art.

In order to achieve the above purpose, the invention provides a method for extracting dendrobium candidum polysaccharide based on a supercritical extraction method, which adopts a phase change device to convert carbon dioxide gas into supercritical fluid, and comprises the following steps:

s1, firstly, putting dried and cut dendrobium candidum into the upper half part of a pressure maintaining tank of an extraction tank, and sealing the tank body;

S2, starting a booster pump to suck air between the extraction tank and the pressure maintaining tank, and enabling the air to enter the pressure maintaining tank to be pressurized to reach the pressure environment in the phase change device;

S3, opening a valve between the phase change device and the extraction tank, and introducing supercritical fluid into the pressure maintaining tank to extract the dendrobium candidum, wherein polysaccharide components in the dendrobium candidum can be gradually dissolved into the supercritical fluid to form an extract;

S4, after the preset time is needed to be dissolved, starting a servo motor in the screening device to drive the material separating plate to rotate, and leaking the extraction liquid in a staggered manner with the separating plate to enter the lower half part of the pressure maintaining tank;

S5, restarting the pressure relief pump to suck air in the pressure maintaining tank, returning the air to the extraction tank to relieve pressure, conducting the air through the extraction tank to quickly dissipate the temperature to the outside, enabling supercritical fluid in the extraction liquid to lose pressure and lose temperature to be converted into carbon dioxide gas, and separating the carbon dioxide gas from polysaccharide liquid to float upwards for layering;

s6, opening the ball valve to release polysaccharide liquid, discharging carbon dioxide gas, and draining the polysaccharide liquid through a pipeline for reuse in the phase change device;

s7, centrifuging and filtering the separated polysaccharide liquid to obtain dendrobium candidum polysaccharide;

The phase change device consists of a high-pressure circulating pump and a heater, wherein the air suction end of the high-pressure circulating pump is connected with a discharge pipe arranged at the bottom of the pressure maintaining tank, and the air pumping end of the high-pressure circulating pump passes through the heater and is connected with a liquid injection pipe arranged at the top of the pressure maintaining tank; the external seal sleeve of the pressure maintaining tank is provided with an extraction tank, one side wall of the bottom of the extraction tank is provided with a booster pump, one side wall of the middle of the extraction tank is provided with a pressure relief pump, and a ball valve is arranged in the discharge pipe; the middle part of pressurize jar is provided with screening plant, screening plant comprises the division board and the branch flitch of coaxial coupling about being, a plurality of sieve silo has been seted up to the top surface of division board, a plurality of hourglass vats have been seted up to the top surface of branch flitch, the externally mounted who draws the jar has and is used for driving the rotation of branch flitch and let a plurality of hourglass vats correspond and communicating servo motor with a plurality of sieve vats.

As a further improvement of the technical scheme, an extraction tank is adopted to seal a pressure maintaining tank to provide a vacuum pressure maintaining and heat preserving environment for the extraction process, and a pressure sensor, a temperature sensor and a controller for monitoring and controlling the internal pressure and temperature of the pressure maintaining tank are arranged at the top of the extraction tank.

As a further improvement of the technical scheme, a feeding nozzle extending into the top of the pressure maintaining tank is embedded in one side of the top of the extracting tank, a cover plate is hinged to the top end opening of the feeding nozzle and can be locked, the liquid injection pipe is embedded between the extracting tank and the top center of the pressure maintaining tank, and the discharging pipe is embedded between the extracting tank and the bottom center of the pressure maintaining tank.

As a further improvement of the technical scheme, a valve rod pipe is embedded in a side wall of the discharge pipe between the extraction tank and the pressure maintaining tank, and penetrates through the side wall of the extraction tank and is in plug-in fit with a valve rod of the ball valve.

As a further improvement of the technical scheme, the pressure maintaining tank is used for extracting dendrobium candidum, a booster pump port is formed in one side of the bottom of the extracting tank, the booster pump is in sleeve joint fit with the booster pump port, a booster pump port is formed in the side wall of the bottom of the pressure maintaining tank and above the booster pump port, the air suction end of the booster pump is arranged in the extracting tank, and the air pumping end of the booster pump is in plug joint fit with the booster pump port.

As a further improvement of the technical scheme, a pressure relief pump port is formed in one side of the middle of the extraction tank, the pressure relief pump is in sleeve joint fit with the pressure relief pump port, a pressure relief port is formed in the side wall of the middle of the pressure maintaining tank and is coaxial with the pressure relief pump port, the air suction end of the pressure relief port is in plug joint fit with the pressure relief pump port, and the pumping end of the pressure relief port is arranged in the extraction tank.

As the further improvement of this technical scheme, adopt screening plant to prop up dendrobium candidum and carry out the extraction, the middle part inner wall welding of pressurize jar has and is annular spacing platform, the division board overlap joint is just cup jointed with pressurize jar looks adaptation on spacing bench, the top surface of division board is sunken state and its bottom surface edge is equipped with the saddle, the transversal L type of personally submitting of saddle, divide the flitch to cup joint with saddle looks adaptation.

As a further improvement of the technical scheme, an output shaft of the servo motor penetrates into the pressure maintaining tank and is coaxially connected with a transmission gear, a toothed ring meshed with the transmission gear is welded at the edge of the bottom surface of the material dividing plate, a jack is formed in the central shaft of the partition plate, a liquid dividing column which is inserted into the jack and can rotate is embedded in the center of the top surface of the material dividing plate, and the top of the liquid dividing column is umbrella-shaped and the outer edge of the liquid dividing column extends to a plurality of screening grooves of the innermost layer.

As a further improvement of the technical scheme, the polysaccharide liquid and the carbon dioxide gas are sequentially discharged by adopting the discharging pipe, a material changing device is arranged at the bottom end of the discharging pipe and comprises a material changing box which is in butt joint with the discharging pipe, a double-pipe channel which is arranged in the material changing box and a deflector rod which is used for switching the double-pipe channel and coaxially connected with the discharging pipe.

As the further improvement of this technical scheme, the reloading box is fan-shaped box structure and its top surface arc edge is equipped with the sleeve pipe, the sleeve pipe is closely cup jointed the cooperation with the row material pipe, the bottom surface of reloading box has been seted up and is used for dodging the pivoted of double-barrelled passageway and dodges the mouth, the top cover of double-barrelled passageway is equipped with sealed the pad, the top surface round mandrel department of reloading box has been seted up and has been changeed the hole, the outside cover of double-barrelled passageway is equipped with the two-way pipe, the one end and the two-way pipe middle part one side extension end grafting cooperation of driving lever.

Compared with the prior art, the invention has the beneficial effects that:

1. According to the method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method, the extraction tank and the pressure maintaining tank are arranged inside and outside, and then a booster pump is started to suck air between the extraction tank and the pressure maintaining tank and enter the pressure maintaining tank to boost the pressure to reach the pressure environment in the phase change device; the vacuum state is formed in the extraction tank, so that the temperature in the pressure maintaining tank is prevented from being lost and the pressure is prevented from being influenced; and through the screening plant that sets up in the pressurize jar, and in the constant temperature constant pressure environment of pressurize jar and be located the process that upper and lower part respectively carries out dendrobe extraction and polysaccharide and separate out for extraction mode succinctly goes on in order, has reduced extraction cost.

2. According to the method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method, the double-pipe channel is switched to be communicated with the discharge pipe in a classified manner through the arranged material changing device, and the double-pipe channel is adjusted to be switched and butted under the sleeve by rotating the deflector rod, so that different substances are discharged to different places, and the classification and collection are facilitated.

Drawings

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes, proportional sizes, and the like of the respective components in the drawings are merely illustrative for aiding in understanding the present invention, and are not particularly limited. Those skilled in the art with access to the teachings of the present invention can select a variety of possible shapes and scale sizes to practice the present invention as the case may be.

FIG. 1 is a plan view of the overall assembly structure of the present invention;

FIG. 2 is a schematic view of the inner wall assembly structure of the extraction tank of the present invention;

FIG. 3 is a front view of FIG. 2 in accordance with the present invention;

FIG. 4 is a schematic diagram of the extraction tank in full section;

FIG. 5 is a schematic view of the assembled structure of the screening apparatus of the present invention;

FIG. 6 is an assembled front view of the screening apparatus of the present invention;

FIG. 7 is a split view of the divider plate and divider plate assembly of the present invention;

Fig. 8 is a schematic view of the assembly structure of the refueling device according to the present invention;

FIG. 9 is a schematic view of a cartridge structure of the present invention;

Fig. 10 is a schematic view of the double tube channel assembly structure of the present invention.

The meaning of each reference sign in the figure is:

100. A phase change device;

200. an extraction tank; 210. a pressure maintaining tank; 211. a limiting table; 212. a booster pump port; 213. a pressurizing port; 214. a pressure discharge pump port; 215. a pressure relief port; 220. a booster pump; 230. a pressure discharge pump; 240. a feeding nozzle; 250. a liquid injection pipe; 260. a discharge pipe; 261. a valve stem tube; 270. a ball valve;

300. A screening device; 310. a partition plate; 311. screening groove; 312. a jack; 313. a support; 320. a material dividing plate; 321. a material leakage groove; 322. a toothed ring; 323. a liquid separating column; 330. a servo motor; 331. a transmission gear;

400. A material changing device; 410. a cartridge changing box; 411. a sleeve; 412. a turning hole; 413. an avoidance port; 420. a double tube channel; 421. a two-way pipe; 422. a sealing gasket; 430. a deflector rod.

Detailed Description

The details of the invention will be more clearly understood in conjunction with the accompanying drawings and description of specific embodiments of the invention. The specific embodiments of the invention described herein are for purposes of illustration only and are not to be construed as limiting the invention in any way. Given the teachings of the present invention, one of ordinary skill in the related art will contemplate any possible modification based on the present invention, and such should be considered to be within the scope of the present invention. The terms "mounted" and "connected" are to be interpreted broadly, as they may be directly connected, or indirectly connected through an intermediary.

The terms "central axis," "vertical," "horizontal," "front," "rear," "upper," "lower," "left," "right," "top," "bottom," "inner," "outer," and the like as used herein are based on the orientation or positional relationship shown in the drawings and are merely for convenience of description and to simplify the description, rather than to indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus should not be construed as limiting the invention. Furthermore, in the description of the invention, the meaning of "a number" is two or more, unless explicitly defined otherwise.

Referring to fig. 1 to 10, the invention provides a method for extracting dendrobium candidum polysaccharide based on a supercritical extraction method, which adopts a phase change device 100 to convert carbon dioxide gas into supercritical fluid, and the supercritical carbon dioxide has special dissolving capacity and can effectively dissolve target substances, such as dendrobium candidum polysaccharide, from raw materials, and comprises the following steps:

S1, firstly, putting the dried and cut dendrobium candidum into the upper half part of a pressure maintaining tank 210 of an extraction tank 200, and sealing the tank body;

s2, starting a booster pump 220 to suck air between the extraction tank 200 and the pressure maintaining tank 210, and enabling the air to enter the pressure maintaining tank 210 to be pressurized to reach the pressure environment in the phase change device 100; the vacuum state is formed in the extraction tank 200, so that the temperature in the pressure maintaining tank 210 is prevented from being lost and the pressure is prevented from being influenced, and the constant temperature and constant pressure environment required in extraction can be stabilized;

S3, opening a valve between the phase change device 100 and the extraction tank 200, and introducing supercritical fluid into the pressure maintaining tank 210 to extract the dendrobium candidum, wherein polysaccharide components in the dendrobium candidum can be gradually dissolved into the supercritical fluid to form an extract;

S4, after the preset time is needed to be dissolved, starting a servo motor 330 in the screening device 300 to drive a material separating plate 320 to rotate, and leaking the extraction liquid in a dislocation way with the material separating plate 310 to enter the lower half part of the pressure maintaining tank 210; the extracted Dendrobium officinale is trapped by the partition plate 310, and is sucked out by a suction pump after the extraction process is finished;

S5, restarting the pressure relief pump 230 to suck air in the pressure maintaining tank 210, flowing back into the extraction tank 200 for pressure relief, conducting the air through the extraction tank 200 for rapid heat dissipation to the outside, enabling supercritical fluid in the extraction liquid to lose pressure and temperature for conversion into carbon dioxide gas, and separating out the carbon dioxide gas from polysaccharide liquid for floating and layering;

s6, opening the ball valve 270 to release polysaccharide liquid, discharging carbon dioxide gas, and draining the polysaccharide liquid through a pipeline for reuse in the phase change device 100;

and S7, centrifuging and filtering the separated polysaccharide liquid to obtain the dendrobium candidum polysaccharide.

The phase change device 100 is composed of a high-pressure circulating pump and a heater, wherein the air suction end of the high-pressure circulating pump is connected with a discharge pipe 260 arranged at the bottom of the pressure maintaining tank 210, and the air pumping end of the high-pressure circulating pump passes through the heater and is connected with a liquid injection pipe 250 arranged at the top of the pressure maintaining tank 210; the carbon dioxide is recovered by a high-pressure circulating pump and is pumped into a pressure maintaining tank 210 for reuse, and the temperature is raised by a heater to reach the condition of supercritical phase change, so that the gaseous carbon dioxide is converted into fluid carbon dioxide; the above devices are prior art and are not described herein in detail;

The extraction tank 200 is arranged on the outer seal sleeve of the pressure maintaining tank 210, and a plurality of supporting rods are welded between the pressure maintaining tank 210 and the extraction tank 200 for enhancing the overall stability; a booster pump 220 is arranged on one side wall of the bottom of the extraction tank 200, a pressure relief pump 230 is arranged on one side wall of the middle of the extraction tank 200, and a ball valve 270 is arranged in a discharge pipe 260; the middle part of the pressure maintaining tank 210 is internally provided with a screening device 300, the screening device 300 consists of a separation plate 310 and a material separating plate 320 which are coaxially connected up and down, a plurality of material sieving grooves 311 are formed in the top surface of the separation plate 310, a plurality of material leaking grooves 321 are formed in the top surface of the material separating plate 320, a servo motor 330 which is used for driving the material separating plate 320 to rotate and enables the material leaking grooves 321 to be correspondingly communicated with the material sieving grooves 311 is arranged outside the extraction tank 200, and therefore the servo motor 330 is started for operation control during material re-separation.

Specifically, the extraction tank 200 is used for sealing the pressure maintaining tank 210 to provide a vacuum pressure maintaining and heat preserving environment for the extraction process, and a pressure sensor, a temperature sensor and a controller for monitoring and controlling the internal pressure and temperature of the pressure maintaining tank 210 are arranged at the top of the extraction tank 200; the controller is a device that changes the wiring of the main circuit or control circuit and changes the resistance value in the circuit in a predetermined sequence to control the starting, speed regulation, braking and reversing of the motor or other equipment. It is typically composed of a program counter, an instruction register, an instruction decoder, a timing generator, an operation controller, and the like; the controller judges and processes the signals from the sensor and other devices according to preset logic and algorithm, and then outputs control signals to adjust the running state of the system; the above devices are prior art and are not described in detail herein.

Further, a feeding nozzle 240 extending into the top of the pressure maintaining tank 210 is embedded in one side of the top of the extracting tank 200, a cover plate is hinged to the top end opening of the feeding nozzle 240 and can be locked, a liquid injection pipe 250 is embedded between the extracting tank 200 and the top center of the pressure maintaining tank 210, and a discharge pipe 260 is embedded between the extracting tank 200 and the bottom center of the pressure maintaining tank 210;

a valve stem pipe 261 is embedded in a side wall of the discharge pipe 260 between the extracting tank 200 and the pressure maintaining tank 210, and the valve stem pipe 261 penetrates through the side wall of the extracting tank 200 and is in plug-in fit with a valve stem of the ball valve 270 so as to operate the discharge pipe 260 to discharge materials at the outside.

Further, the dendrobium candidum is extracted by adopting the pressure maintaining tank 210, a booster pump port 212 is formed in one side of the bottom of the extracting tank 200, a booster pump 220 is in sleeve joint fit with the booster pump port 212, a booster port 213 is formed in the side wall of the bottom of the pressure maintaining tank 210 and above the booster pump port 212, the air suction end of the booster pump 220 is arranged in the extracting tank 200, and the air suction end of the booster pump 220 is in sleeve joint fit with the booster pump port 212 so as to pump air in the extracting tank 200 into the pressure maintaining tank 210 for boosting;

A pressure relief pump port 214 is formed in one side of the middle part of the extraction tank 200, a pressure relief pump 230 is in sleeve joint fit with the pressure relief pump port 214, a pressure relief port 215 is formed in the side wall of the middle part of the pressure maintaining tank 210 and is coaxial with the pressure relief pump port 214, the air suction end of the pressure relief port 215 is in plug joint fit with the pressure relief pump port 214, and the air pumping end of the pressure relief port 215 is arranged in the extraction tank 200 so as to pump air in the pressure maintaining tank 210 into the extraction tank 200 for pressure relief.

Besides, the screening device 300 is used for supporting dendrobium candidum for extraction, the annular limiting table 211 is welded on the inner wall of the middle part of the pressure maintaining tank 210, and the partition plate 310 is lapped on the limiting table 211 and is in fit and sleeve joint with the pressure maintaining tank 210; the top surface of the partition plate 310 is in a concave state, a supporting table 313 is arranged at the edge of the bottom surface of the partition plate, the cross section of the supporting table 313 is L-shaped, and the material distributing plate 320 is sleeved with the supporting table 313 in an adapting way, so that the material distributing plate 320 is attached to the bottom surface of the partition plate 310 and can rotate in a suspending way, and a plurality of material leaking grooves 321 are correspondingly communicated with a plurality of material sieving grooves 311 or are sealed in a dislocation way.

An output shaft of the servo motor 330 penetrates into the pressure maintaining tank 210 and is coaxially connected with a transmission gear 331, and a toothed ring 322 meshed with the transmission gear 331 is welded at the edge of the bottom surface of the material dividing plate 320; the center shaft of the partition plate 310 is provided with a jack 312, the center of the top surface of the material separating plate 320 is embedded with a rotatable material separating column 323 which is inserted into the jack 312, the top of the material separating column 323 is umbrella-shaped, the outer edge of the material separating column 323 extends to the positions of a plurality of material sieving grooves 311 of the innermost layer, the material separating column 323 further stabilizes the assembly effect of the material separating plate 320 and the partition plate 310, and the umbrella-shaped dispersion liquid at the top of the material separating column 323 is utilized to be discharged to the plurality of material sieving grooves 311 of the innermost layer.

Specifically, the polysaccharide liquid and the carbon dioxide gas are sequentially discharged by adopting the discharge pipe 260, the bottom end of the discharge pipe 260 is provided with a material changing device 400, and the material changing device 400 comprises a material changing box 410 which is in butt joint with the discharge pipe 260, a double-pipe channel 420 which is arranged in the material changing box 410, and a deflector rod 430 which is used for switching the double-pipe channel 420 to be coaxially connected with the discharge pipe 260;

The reloading box 410 is of a fan-shaped box structure, a sleeve 411 is arranged at the arc edge of the top surface of the reloading box 410, the sleeve 411 is in tight sleeve joint with the discharging pipe 260, a avoiding opening 413 for avoiding the rotation of the double-pipe channel 420 is formed in the bottom surface of the reloading box 410, a sealing pad 422 is sleeved at the top end of the double-pipe channel 420, a rotating hole 412 is formed in the round mandrel of the top surface of the reloading box 410, a double-way pipe 421 is sleeved outside the double-pipe channel 420, and one end of a deflector rod 430 is in plug joint with one extending end of the middle part of the double-way pipe 421; the double tube channel 420 is adjusted to switch the docking under the sleeve 411 by turning the lever 430 to discharge different substances to different places for sorting collection.

It should be noted that, in the present invention, the holes or openings on the walls of the extraction tank 200 and the pressure maintaining tank 210 are sealed, for example, the wall of the extraction tank 200 is sealed by a sealing sleeve, and the wall of the pressure maintaining tank 210 is sealed mechanically; the mechanical seal is generally composed of a movable ring, a stationary ring, a spring, an auxiliary sealing piece and the like, and an extremely thin liquid film is formed through relative movement between the movable ring and the stationary ring, so that the seal is realized; the sealing mode has the advantages of good sealing performance and long service life, and is the prior art and is not described herein.

It should be noted that the foregoing embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the present invention and implement the same, not to limit the scope of the present invention. All equivalent changes or modifications made in accordance with the spirit of the present invention should be construed to be included in the scope of the present invention.

Claims (10)

1. A method for extracting dendrobium candidum polysaccharide based on a supercritical extraction method adopts a phase change device (100) to convert carbon dioxide gas into supercritical fluid, and is characterized in that: the method comprises the following steps:

S1, firstly, putting the dried and cut dendrobium candidum into the upper half part of a pressure maintaining tank (210) of an extraction tank (200), and sealing a tank body;

S2, starting a booster pump (220) to suck air between the extraction tank (200) and the pressure maintaining tank (210), and enabling the air to enter the pressure maintaining tank (210) to be pressurized to reach the pressure environment in the phase change device (100);

s3, opening a valve between the phase change device (100) and the extraction tank (200), and introducing supercritical fluid into the pressure maintaining tank (210) to extract the dendrobium candidum, wherein polysaccharide components in the dendrobium candidum can be gradually dissolved into the supercritical fluid to form an extraction liquid;

s4, after the preset time is needed to be dissolved, a servo motor (330) in the screening device (300) is started to drive the material separating plate (320) to rotate, and extraction liquid is leaked out in a staggered manner from the separating plate (310) and enters the lower half part of the pressure maintaining tank (210);

S5, restarting the pressure relief pump (230) to suck air in the pressure maintaining tank (210) and return the air to the extraction tank (200) for pressure relief, conducting the air through the extraction tank (200) for rapid heat dissipation to the outside, enabling supercritical fluid in the extraction liquid to lose pressure and temperature to be converted into carbon dioxide gas, and precipitating the carbon dioxide gas from polysaccharide liquid for floating and layering;

S6, opening a ball valve (270) to release polysaccharide liquid, discharging carbon dioxide gas, and draining the polysaccharide liquid through a pipeline for recycling in the phase change device (100);

s7, centrifuging and filtering the separated polysaccharide liquid to obtain dendrobium candidum polysaccharide;

The phase change device (100) consists of a high-pressure circulating pump and a heater, wherein the air suction end of the high-pressure circulating pump is connected with a discharge pipe (260) arranged at the bottom of the pressure maintaining tank (210), and the air pumping end of the high-pressure circulating pump passes through the heater and is connected with a liquid injection pipe (250) arranged at the top of the pressure maintaining tank (210); the external sealing sleeve of the pressure maintaining tank (210) is provided with an extraction tank (200), one side wall of the bottom of the extraction tank (200) is provided with a booster pump (220), one side wall of the middle of the extraction tank (200) is provided with a pressure relief pump (230), and a ball valve (270) is arranged in the discharge pipe (260); be provided with screening plant (300) in the middle part of pressurize jar (210), screening plant (300) are by being upper and lower coaxial coupling's division board (310) and branch flitch (320) are constituteed, a plurality of sieve silo (311) have been seted up to the top surface of division board (310), a plurality of hourglass silo (321) have been seted up to the top surface of branch flitch (320), the externally mounted who draws jar (200) has and is used for driving branch flitch (320) rotation and lets a plurality of hourglass silo (321) correspond and communicating servo motor (330) with a plurality of sieve silo (311).

2. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 1, which is characterized in that: the extraction tank (200) is used for sealing the pressure maintaining tank (210) to provide a vacuum pressure maintaining and heat preserving environment for the extraction process, and a pressure sensor, a temperature sensor and a controller for monitoring and controlling the internal pressure and temperature of the pressure maintaining tank (210) are arranged at the top of the extraction tank (200).

3. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 2, which is characterized in that: the extracting tank is characterized in that a feeding nozzle (240) extending into the top of the pressure maintaining tank (210) is embedded on one side of the top of the extracting tank (200), a cover plate is hinged to the top end opening of the feeding nozzle (240) and can be locked, a liquid injection pipe (250) is embedded between the extracting tank (200) and the top center of the pressure maintaining tank (210), and a discharge pipe (260) is embedded between the extracting tank (200) and the bottom center of the pressure maintaining tank (210).

4. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 3, which is characterized in that: a valve rod pipe (261) is embedded in one side wall of the discharge pipe (260) between the extraction tank (200) and the pressure maintaining tank (210), and the valve rod pipe (261) penetrates through the side wall of the extraction tank (200) and is in plug-in fit with a valve rod of the ball valve (270).

5. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 4, which is characterized in that: the dendrobium candidum extracting device is characterized in that a pressure maintaining tank (210) is used for extracting dendrobium candidum, a booster pump opening (212) is formed in one side of the bottom of the extracting tank (200), a booster pump (220) is in sleeve joint fit with the booster pump opening (212), a booster pump opening (213) is formed in the side wall of the bottom of the pressure maintaining tank (210) and above the booster pump opening (212), an air suction end of the booster pump (220) is arranged in the extracting tank (200), and a pumping end of the booster pump is in plug joint fit with the booster pump opening (212).

6. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 5, which is characterized in that: the extraction tank is characterized in that a pressure relief pump port (214) is formed in one side of the middle of the extraction tank (200), the pressure relief pump (230) is in sleeve joint fit with the pressure relief pump port (214), a pressure relief port (215) is formed in the side wall of the middle of the pressure maintaining tank (210) and is coaxially formed with the pressure relief pump port (214), the air suction end of the pressure relief port (215) is in plug joint fit with the pressure relief pump port (214), and the pumping end of the pressure relief pump is arranged in the extraction tank (200).

7. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 6, which is characterized in that: adopt screening plant (300) to prop up dendrobium candidum and carry out the extraction, the middle part inner wall welding of pressurize jar (210) has and is annular spacing platform (211), division board (310) overlap joint just cup joints with pressurize jar (210) looks adaptation on spacing platform (211), the top surface of division board (310) is the concave state and its bottom surface edge is equipped with saddle (313), the transversal L type of personally submitting of saddle (313), divide flitch (320) and saddle (313) looks adaptation to cup joint.

8. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 7, which is characterized in that: the output shaft of servo motor (330) runs through to in pressurize jar (210) and coaxial coupling has drive gear (331), the bottom surface edge welding of feed divider (320) has toothed ring (322) with drive gear (331) meshing, jack (312) have been seted up in center pin department of division board (310), the top surface center of feed divider (320) has inlayed and has pegged graft and rotatable branch liquid column (323) with jack (312), the top of branch liquid column (323) is umbrella form and its outward flange extends to a plurality of sieve feed grooves (311) department of inlayer.

9. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 8, which is characterized in that: polysaccharide liquid and carbon dioxide gas are sequentially discharged through a discharge pipe (260), a material changing device (400) is arranged at the bottom end of the discharge pipe (260), and the material changing device (400) comprises a material changing box (410) in butt joint with the discharge pipe (260), a double-pipe channel (420) arranged inside the material changing box (410) and a deflector rod (430) used for switching the double-pipe channel (420) to be coaxially connected with the discharge pipe (260).

10. The method for extracting dendrobium candidum polysaccharide based on the supercritical extraction method according to claim 9, which is characterized in that: the utility model discloses a double-barreled automatic feeding device, including double-barreled channel (420), charging box (410), driving lever (430), driving lever (421), sealing pad (422) are set up in the top cover of double-barreled channel (420), change box (410) are fan-shaped box structure and its top surface arc edge be equipped with sleeve pipe (411), sleeve pipe (411) closely cup joints cooperation with discharging pipe (260), dodge mouth (413) that are used for dodging double-barreled channel (420) pivoted are seted up to the bottom surface of charging box (410), change hole (412) have been seted up in top surface round mandrel department of charging box (410), the outside cover of double-barreled channel (420) is equipped with double-pass pipe (421), the one end and the extension of double-pass pipe (421) middle part one side of driving lever (430) are pegged graft and are cooperated.