Freeze dryer and preparation process of freeze-dried chrysanthemum morifolium sweet leaf

Abstract

The application relates to the technical field of heat exchange equipment, and discloses a freeze-drying machine and a preparation process of freeze-dried sweetleaf chrysanthemum powder. The refrigerant provided by a compression refrigeration mechanism to each cooling support plate can lower the temperature inside a freezing cavity and maintain a low-temperature environment, and a negative pressure suction mechanism can suck the gas inside the freezing cavity, so that the negative pressure environment of the freezing cavity is maintained. The material inside each cooling tray is subjected to freeze-drying through the negative pressure and the low-temperature environment. During the freeze-drying process, external air is sucked in through an air flow cooling mechanism, and the external air is injected into the freezing cavity after being cooled by the refrigerant provided by the compression refrigeration mechanism. The air medium for the moisture flow inside the freezing cavity is provided, and the suction effect of the negative pressure suction mechanism promotes the discharge of the high-humidity gas inside the freezing cavity, so that the high-humidity environment in each region inside the freezing cavity is fully squeezed out through gas renewal, and the freeze-drying process inside the freezing cavity is promoted, and the freeze-drying effect is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat exchange equipment, in particular to a freeze-drying machine and a preparation process of freeze-dried sweet leaf chrysanthemum powder. BACKGROUND

[0002] Freeze-drying (also known as lyophilization) is a process that removes water from materials by sublimation, widely used in food, pharmaceutical, biological products and other fields. Currently, freeze-drying machines mainly rely on mechanical refrigeration and vacuum pump technology, but due to low refrigeration efficiency and high energy consumption, they are only suitable for small-scale production. With the progress of refrigeration technology, vacuum technology and control system, modern freeze-drying machines have precise temperature and pressure control capabilities and can realize continuous production.

[0003] Solution freeze-drying is a special lyophilization process suitable for the preservation of heat-sensitive substances such as proteins, vaccines and antibiotics. The core of this process is to quickly freeze the solution to form a uniform ice crystal structure, and then sublimate the water in a vacuum environment. In the pharmaceutical and biotechnology fields, solution freeze-drying is a key step in the preparation of freeze-dried powder injections. In the traditional process, the solution is divided into Westlin bottles or trays and then placed in a freeze-drying machine. The removal of water depends on the direct sublimation of ice crystals, but the water vapor after sublimation needs to pass through the porous structure of the drying layer to reach the cold trap. As the thickness of the drying layer increases, the mass transfer resistance increases significantly, resulting in a decrease in sublimation rate. At the same time, due to the lack of water flow medium, the water vapor after sublimation of ice crystals only relies on diffusion to migrate to the cold trap, resulting in high mass transfer resistance, low water diffusion speed, and thus low drying rate. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a freeze-drying machine and a preparation process of freeze-dried sweet leaf chrysanthemum powder.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] The application discloses a freeze dryer, which comprises a freezing cabinet, a structure shell and a heat preservation shell, a heat preservation cabinet door is arranged on the front of the freezing cabinet, and the heat preservation cabinet door and the heat preservation shell jointly form a closed freezing cavity after being closed; a plurality of cooling support plates are arranged in the freezing cavity, and one cooling tray can be accommodated between two adjacent cooling support plates; the cooling tray is used for containing freeze-dried raw materials; a compression refrigeration mechanism, an airflow cooling mechanism and a negative pressure suction mechanism are arranged outside the freezing cabinet; the compression refrigeration mechanism can provide refrigerant to each cooling support plate and the airflow cooling mechanism; the negative pressure suction mechanism can suck the gas in the freezing cavity and maintain the negative pressure environment of the freezing cavity; and the airflow cooling mechanism can suck external air, inject the external air into the freezing cavity after being cooled by the refrigerant provided by the compression refrigeration mechanism, and promote the discharge of high-humidity gas in the freezing cavity in cooperation with the suction of the negative pressure suction mechanism.

[0007] Preferably, the cooling support plate comprises a heat conduction plate body, the top end of the heat conduction plate body is provided with an elastic clamping track, the bottom end of the cooling tray is provided with a conduction sliding block, the thickness of the conduction sliding block is smaller than the depth of the elastic clamping track, and the end of the elastic clamping track close to the heat preservation cabinet door has an expanded opening; the elastic clamping track comprises symmetrically arranged elastic clamping pieces, the bottom end of the elastic clamping piece is welded and fixed with the heat conduction plate body, and the elastic clamping piece can be deformed; when the conduction sliding block slides into the elastic clamping track, the two elastic clamping pieces can tightly abut against the conduction sliding block.

[0008] Preferably, the compression refrigeration mechanism comprises a refrigerant output pipe and a refrigerant recovery pipe, the refrigerant output pipe is communicated with a freezing heat exchange pipe and an airflow heat exchange pipe through a distribution valve; the end of the freezing heat exchange pipe extending into the heat preservation shell is provided with an input joint, the end of the refrigerant recovery pipe extending into the heat preservation shell is provided with a return joint, and the airflow heat exchange pipe is communicated with the refrigerant recovery pipe after passing through the airflow cooling mechanism.

[0009] Preferably, the bottom end of the heat conduction plate body is provided with a heat conduction coil pipe, the pipe wall of the heat conduction coil pipe is in contact with the heat conduction plate body for heat transfer, the two ends of the heat conduction coil pipe are respectively connected with the input joint and the return joint, and each cooling support plate can be integrally removed from the freezing cavity; when the two ends of the heat conduction coil pipe are not connected with the input joint and the return joint, the input joint and the return joint are closed.

[0010] Preferably, the air flow cooling mechanism comprises an air flow heat exchanger, one side of the air flow heat exchanger is provided with an air flow inlet, the air flow inlet is in communication with the inside of the freezing cavity through an air flow input pipe; the air flow input pipe and the air flow heat exchanger pipe both pass through the air flow heat exchanger, and the gas inside the air flow input pipe and the refrigerant inside the air flow heat exchanger pipe exchange heat inside the air flow heat exchanger; the air flow input pipe is also in communication with a booster pump, which can provide power for the delivery of air flow from the air flow inlet to the inside of the freezing cavity.

[0011] Preferably, the negative pressure suction mechanism comprises an air suction pipeline and an air suction pump, the air suction pump is arranged inside the air suction pipeline, one end of the air suction pipeline extending into the inside of the freezing cavity is provided with a one-way air valve, the exhaust direction of the one-way air valve is from the freezing cavity to the air suction pump; one end of the air suction pipeline away from the freezing cavity is provided with a liquid collecting tank, which is used to collect the moisture in the humid cold air output from the freezing cavity.

[0012] Preferably, the inside of the freezing cavity is also provided with a plurality of material scraping mechanisms, each of the material scraping mechanisms is arranged above the cooling support plate, the bottom end of the heat conduction plate body of each cooling support plate is provided with a condensation baffle; the height of the condensation baffle near one end of the heat preservation cabinet door is higher than the height of the condensation baffle away from the heat preservation cabinet door, the depth of the cooling tray near one end of the heat preservation cabinet door is lower than the depth of the cooling tray away from the heat preservation cabinet door; the material scraping mechanism can scrape the material inside each cooling tray to the end near the heat preservation cabinet door after the freezing and drying is completed, and at the same time, the ice crystals condensed at the bottom end of the condensation baffle are scraped to the end away from the heat preservation cabinet door.

[0013] Preferably, the material scraping mechanism comprises a material scraping mounting bracket, an upper layer scraping plate and a lower layer scraping plate; the upper layer scraping plate comprises an upper layer driving rod and an upper layer scraper, the upper layer driving rod and the upper layer scraper are elastically connected through a plurality of upper layer elastic connection columns; the lower layer scraping plate comprises a lower layer driving rod and a lower layer scraper, the lower layer driving rod and the lower layer scraper are elastically connected through a plurality of lower layer elastic connection columns; the material scraping mounting bracket is provided with an upper layer guide groove and a lower layer guide groove, the upper layer driving rod and the lower layer driving rod respectively penetrate the upper layer guide groove and the lower layer guide groove.

[0014] Preferably, one side of the material scraping mounting support is provided with a material scraping driving sprocket, a plurality of upper supporting sprockets and a plurality of lower supporting sprockets, the material scraping driving sprocket and the plurality of upper supporting sprockets are externally sleeved with an upper driving chain, and the material scraping driving sprocket and the plurality of lower supporting sprockets are externally sleeved with a lower driving chain; the upper driving chain is fixed between the upper driving rod and one end of the upper layer driving rod, and the lower driving chain is fixed between the lower driving rod and one end of the lower layer driving rod; the structure shell is internally provided with a material scraping driving mechanism outside the heat preservation shell, the material scraping driving mechanism comprises a plurality of material scraping driving units, each material scraping mechanism at the same layer is driven by the same material scraping driving unit; the material scraping driving unit comprises a material scraping driving motor and a material scraping driving shaft, the material scraping driving motor is in power transmission between the material scraping driving shaft through a speed reducer, and the material scraping driving shaft is coaxially fixed with each material scraping driving sprocket at the same layer.

[0015] A preparation process of mountain sweet stevia freeze-dried powder, using the above-mentioned freeze-drying machine to freeze-dry mountain sweet stevia concentrated solution, comprising the following steps:

[0016] Sweet stevia powder and mountain sweet powder are respectively weighed and extracted in water to obtain mountain sweet stevia extract;

[0017] The obtained mountain sweet stevia extract is concentrated to obtain mountain sweet stevia concentrated solution;

[0018] The mountain sweet stevia concentrated solution is quantitatively placed in the cooling tray, and each cooling tray is placed in the freezing cavity for freeze-drying to obtain mountain sweet stevia freeze-dried powder.

[0019] Compared with the prior art, the present application provides a freeze-drying machine and a preparation process of mountain sweet stevia freeze-dried powder, which has the following beneficial effects:

[0020] 1. The freeze-drying machine, by the refrigerant provided by the compression refrigeration mechanism to each cooling support plate, the inside of the freezing cavity is cooled and a low-temperature environment is maintained, and by the negative pressure suction mechanism, the gas in the freezing cavity can be sucked to maintain the negative pressure environment of the freezing cavity, so that the material in each cooling tray is freeze-dried by negative pressure and low-temperature environment, and during the freeze-drying process, the air flow cooling mechanism inhales external air, and the external air is cooled by the refrigerant provided by the compression refrigeration mechanism and then injected into the freezing cavity, providing air medium for the moisture flow in the freezing cavity, and cooperating with the suction effect of the negative pressure suction mechanism to promote the high-humidity gas in the freezing cavity to be discharged, so that the high-humidity environment in each area of the freezing cavity is fully squeezed out by gas replacement, so as to promote the freeze-drying process in the freezing cavity and improve the freeze-drying effect.

[0021] 2. This type of freeze dryer features an expansion opening at the end of the elastic clamping track near the insulated cabinet door, facilitating the sliding block at the bottom of the cooling tray to slide into the corresponding elastic clamping track. In actual use, both the cooling tray and the heat-conducting plate are made of copper alloy. The elasticity of the clamping pieces ensures stable clamping and contact between the clamping pieces and the sliding block, maximizing the contact area between the bottom of the cooling tray and the cooling support plate. This avoids the problem of insufficient contact area caused by uneven surfaces during normal placement, ensuring efficient heat transfer between the cooling support plate and the cooling tray.

[0022] 3. In this type of freeze dryer, the refrigerant enters the heat-conducting coil through the inlet connector, and heat is transferred between the coil wall and the heat-conducting plate to effectively control the temperature of the environment near the heat-conducting plate, thereby ensuring the freezing and heat preservation effect on the material inside the cooling tray. After heat exchange, the refrigerant is output to the refrigerant recovery pipe through the return connector to refresh the temperature of the refrigerant and circulate to provide low-temperature refrigerant to the heat-conducting coil. The two ends of the heat-conducting coil are connected to the inlet connector and the return connector respectively, which can be adjusted to adjust the spatial distribution inside the freezing chamber by adding or removing cooling support plates, thereby improving the adaptability of the material inside the freezing chamber for freeze drying.

[0023] 4. In this type of freeze dryer, the gas inside the airflow inlet pipe exchanges heat with the refrigerant inside the airflow heat exchanger. A booster pump provides the power to transport the airflow from the airflow inlet into the freeze chamber, thereby delivering the gas cooled to the ambient temperature inside the freeze chamber to avoid damaging the low-temperature environment inside the freeze chamber. It can also provide the air medium for the flow of moisture inside the freeze chamber through the injection of cold, dry air, promoting the uniform distribution of humidity inside the freeze chamber. This ensures the efficiency of the high-humidity gas discharged by the negative pressure generated by the suction pump, promoting the freeze-drying process inside the freeze chamber.

[0024] 5. This type of freeze dryer uses scraper drive motors to drive scraper drive shafts, which in turn drive scraper drive sprockets on the same layer to rotate. This drives the upper and lower drive chains to move in opposite directions, which in turn drives the upper and lower drive rods to move in opposite directions. The ice crystals condensed at the bottom of the condensation baffle are scraped away from the insulated cabinet door, while the dried material is scraped away from the insulated cabinet door. This allows for the collection of dried material by scraping it towards the end closest to the insulated cabinet door, thereby improving the efficiency of collecting the dried material. Attached Figure Description

[0025] Figure 1 This is one of the three-dimensional structural schematic diagrams of a freeze dryer according to the present invention;

[0026] Figure 2An internal structure diagram of a freeze dryer according to the present application;

[0027] Figure 3 A second perspective structure diagram of a freeze dryer according to the present application;

[0028] Figure 4 A third perspective structure diagram of a freeze dryer according to the present application;

[0029] Figure 5 A fourth perspective structure diagram of a freeze dryer according to the present application;

[0030] Figure 6 A perspective structure diagram of a scraping drive mechanism of a freeze dryer according to the present application and each cooling support plate, each cooling tray and each scraping mechanism of the same layer;

[0031] Figure 7 A first perspective structure diagram of two cooling support plates, a cooling tray and a scraping mechanism of a freeze dryer according to the present application;

[0032] Figure 8 A second perspective structure diagram of two cooling support plates, a cooling tray and a scraping mechanism of a freeze dryer according to the present application;

[0033] Figure 9 A third perspective structure diagram of two cooling support plates, a cooling tray and a scraping mechanism of a freeze dryer according to the present application;

[0034] Figure 10 A first perspective structure diagram of a cooling tray and a scraping mechanism of a freeze dryer according to the present application;

[0035] Figure 11 A second perspective structure diagram of a cooling tray and a scraping mechanism of a freeze dryer according to the present application.

[0036] In the figure: 1, freezer body; 11, structural shell; 12, heat preservation shell; 2, heat preservation cabinet door; 3, cooling support plate; 31, heat conduction plate body; 32, elastic clamping track; 321, elastic clamping piece; 33, heat conduction coil; 34, condensation baffle; 4, cooling tray; 41, conduction slider; 5, compression refrigeration mechanism; 51, refrigerant output pipe; 52, refrigerant recovery pipe; 53, distribution valve; 54, refrigeration heat exchange pipe; 55, air flow heat exchange pipe; 56, input joint; 57, return joint; 6, air flow cooling mechanism; 61, air flow heat exchanger; 62, air flow inlet; 63, air flow input pipe; 64, booster pump; 7, negative pressure suction mechanism; 71, air suction pipeline; 72, air suction pump; 73, one-way air valve; 74, liquid collection tank; 8, scraping mechanism; 81, scraping installation support; 811, upper layer guide groove; 812, lower layer guide groove; 82, upper layer scraper; 821, upper layer driving rod; 822, upper layer scraper; 823, upper layer elastic connecting column; 83, lower layer scraper; 831, lower layer driving rod; 832, lower layer scraper; 833, lower layer elastic connecting column; 84, scraping drive sprocket; 85, upper support sprocket; 86, lower support sprocket; 87, upper drive chain; 88, lower drive chain; 9, scraping drive mechanism; 91, scraping drive unit; 911, scraping drive motor; 912, scraping drive shaft. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0038] As introduced in the background, the deficiencies in the prior art exist. In order to solve the above technical problems, the present application proposes a freeze-drying machine and a preparation process of freeze-dried sweet leaf chrysanthemum powder. Embodiment one:

[0039] Please refer to Figures 1-11The application relates to a freeze dryer, which comprises a freezing cabinet 1, the freezing cabinet 1 comprising a structural shell 11 and a heat-insulating shell 12, and a heat-insulating cabinet door 2 arranged on the front of the freezing cabinet 1, the heat-insulating cabinet door 2 being capable of forming a closed freezing cavity together with the heat-insulating shell 12 after being closed, and a plurality of cooling support plates 3 being arranged in the freezing cavity, each of the cooling support plates 3 being capable of accommodating one cooling tray 4 between two adjacent cooling support plates 3, and the cooling tray 4 being used for containing raw materials for freeze drying; a compression refrigeration mechanism 5, an air flow cooling mechanism 6 and a negative pressure suction mechanism 7 are arranged outside the freezing cabinet 1, the compression refrigeration mechanism 5 being capable of providing refrigerant to each of the cooling support plates 3 and the air flow cooling mechanism 6, the negative pressure suction mechanism 7 being capable of sucking the gas in the freezing cavity and maintaining the negative pressure environment of the freezing cavity, and the air flow cooling mechanism 6 being capable of sucking the external air and injecting the external air into the freezing cavity after being cooled by the refrigerant provided by the compression refrigeration mechanism 5, and promoting the high-humidity gas in the freezing cavity to be discharged in cooperation with the suction of the negative pressure suction mechanism 7.

[0040] In use, the materials to be freeze-dried (which can be solid materials or liquid materials, wherein the solid materials need to be laid in the cooling tray 4) are respectively quantitatively placed in each of the cooling trays 4, and then each of the cooling trays 4 is placed on the top end of each of the cooling support plates 3 (the top end of each of the cooling support plates 3 on the top layer is not provided with the cooling tray 4), and then the heat-insulating cabinet door 2 is closed to seal the freezing cavity, the refrigerant provided by the compression refrigeration mechanism 5 to each of the cooling support plates 3 is used for lowering the temperature in the freezing cavity and maintaining the low-temperature environment, and the negative pressure suction mechanism 7 is used for sucking the gas in the freezing cavity and maintaining the negative pressure environment of the freezing cavity, so that the materials in each of the cooling trays 4 are freeze-dried through the negative pressure and the low-temperature environment, and in the freeze-drying process, the air flow cooling mechanism 6 is used for sucking the external air (and in specific use, other protective gases such as inert gases can be selected according to the drying process of the materials), and the external air is injected into the freezing cavity after being cooled by the refrigerant provided by the compression refrigeration mechanism 5, air medium for water flow in the freezing cavity is provided, and the suction of the negative pressure suction mechanism 7 is used for promoting the high-humidity gas in the freezing cavity to be discharged, so that the high-humidity environment in each of the regions in the freezing cavity is sufficiently squeezed out through gas renewal, and the freeze-drying process in the freezing cavity is promoted, and the freeze-drying effect is improved. Embodiment two

[0041] Please refer to Figures 1-11The difference from the above-mentioned embodiments is that the cooling support plate 3 comprises a heat-conducting plate body 31, the top end of the heat-conducting plate body 31 is provided with an elastic clamping track 32, the bottom end of the cooling tray 4 is provided with a conduction sliding block 41, the thickness of the conduction sliding block 41 is smaller than the depth of the elastic clamping track 32, and the end of the elastic clamping track 32 close to the heat preservation cabinet door 2 has an expanded opening; the elastic clamping track 32 comprises symmetrically arranged elastic clamping pieces 321, the bottom end of the elastic clamping piece 321 is welded and fixed with the heat-conducting plate body 31, and the elastic clamping piece 321 can be deformed; when the conduction sliding block 41 slides into the elastic clamping track 32, both of the elastic clamping pieces 321 can tightly abut against the conduction sliding block 41.

[0042] The compression refrigeration mechanism 5 comprises a refrigerant output pipe 51 and a refrigerant recovery pipe 52, the refrigerant output pipe 51 is communicated with a refrigeration heat exchange pipe 54 and an airflow heat exchange pipe 55 through a distribution valve 53; the refrigeration heat exchange pipe 54 is provided with an input joint 56 at the end extending into the inside of the heat preservation shell 12, the refrigerant recovery pipe 52 is provided with a backflow joint 57 at the end extending into the inside of the heat preservation shell 12, and the airflow heat exchange pipe 55 is communicated with the refrigerant recovery pipe 52 after passing through the airflow cooling mechanism 6.

[0043] The bottom end of the heat-conducting plate body 31 is provided with a heat-conducting coil pipe 33, the pipe wall of the heat-conducting coil pipe 33 is in contact with the heat-conducting plate body 31 for heat transfer; the two ends of the heat-conducting coil pipe 33 are respectively connected with the input joint 56 and the backflow joint 57, and each cooling support plate 3 can be removed from the inside of the refrigeration cavity as a whole; when the two ends of the heat-conducting coil pipe 33 are not connected with the input joint 56 and the backflow joint 57, the input joint 56 and the backflow joint 57 are closed.

[0044] In specific use, through the setting of the elastic clamping track 32 of the cooling support plate 3, when the cooling tray 4 is placed on the top end of the cooling support plate 3, the expanded opening of the elastic clamping track 32 close to the heat preservation cabinet door 2 facilitates the conduction sliding block 41 at the bottom of the cooling tray 4 to slide into the corresponding elastic clamping track 32; in specific use, the overall material of the cooling tray 4 (including the conduction sliding block 41) and the overall material of the heat-conducting plate body 31 are all copper alloy, so that the elastic clamping piece 321 can stably clamp and contact with the conduction sliding block 41 through the elastic effect of the elastic clamping piece 321 itself, so as to fully ensure and increase the sufficient contact area between the bottom of the cooling tray 4 and the cooling support plate 3, avoid the problem of small contact area caused by uneven surface in conventional placement, and ensure the heat conduction efficiency between the cooling support plate 3 and the cooling tray 4.

[0045] And in use, the refrigerant output pipe 51 of the compression refrigeration mechanism 5 outputs refrigerant to the refrigeration heat exchange pipe 54 through the distribution valve 53 (the refrigerant is the common refrigerant in the prior art, and it is ensured that the refrigerant remains in a flowing state during freeze-drying), the refrigerant enters the heat conduction coil 33 through the input joint 56, and the heat conduction coil 33 is in contact with the heat conduction plate body 31 to effectively control the temperature of the environment near the heat conduction plate body 31, thereby ensuring the freezing and insulation effect of the material in the cooling tray 4 (each cooling tray 4 is cooled in the upward and downward directions by the heat conduction coil 33). The heat-exchanged refrigerant is output to the refrigerant recovery pipe 52 through the backflow joint 57 to update the temperature of the refrigerant, so as to circulate the low-temperature refrigerant to the heat conduction coil 33; and in specific use, the two ends of the heat conduction coil 33 are respectively connected to the input joint 56 and the backflow joint 57, and each cooling support plate 3 can be removed from the inside of the freezing cavity; when the two ends of the heat conduction coil 33 are not connected to the input joint 56 and the backflow joint 57, the input joint 56 and the backflow joint 57 are closed, and can be adjusted according to the increase or decrease of the cooling support plate 3 to adjust the space distribution inside the freezing cavity and improve the adaptability of the material freeze-drying inside the freezing cavity. Example three:

[0046] Please refer to Figures 1-11 The difference from the above-mentioned embodiments is that the air flow cooling mechanism 6 comprises an air flow heat exchanger 61, one side of the air flow heat exchanger 61 is provided with an air flow inlet 62, the air flow inlet 62 is communicated with the inside of the freezing cavity through an air flow input pipe 63; the air flow input pipe 63 and the air flow heat exchange pipe 55 both pass through the air flow heat exchanger 61, and the gas inside the air flow input pipe 63 and the refrigerant inside the air flow heat exchange pipe 55 exchange heat in the air flow heat exchanger 61; the air flow input pipe 63 is also communicated with a booster pump 64, and the booster pump 64 can provide power for the air flow to be transported from the air flow inlet 62 to the inside of the freezing cavity.

[0047] The negative pressure suction mechanism 7 comprises an air suction pipeline 71 and an air suction pump 72, the air suction pump 72 is arranged in the air suction pipeline 71, one end of the air suction pipeline 71 extending into the freezing cavity is provided with a one-way air valve 73, the exhaust direction of the one-way air valve 73 is from the freezing cavity to the air suction pump 72; the end of the air suction pipeline 71 away from the freezing cavity is provided with a liquid collecting tank 74, and the liquid collecting tank 74 is used to collect the water in the humid cold air output from the freezing cavity.

[0048] In specific use, the refrigerant output pipe 51 of the compression refrigeration mechanism 5 inputs refrigerant to the airflow heat exchange pipe 55 through the distribution valve 53, the airflow input pipe 63 and the airflow heat exchange pipe 55 both pass through the airflow heat exchanger 61, and the gas inside the airflow input pipe 63 exchanges heat with the refrigerant inside the airflow heat exchange pipe 55 inside the airflow heat exchanger 61, and the airflow from the airflow inlet 62 to the inside of the freezing chamber is driven by the booster pump 64 to deliver the gas cooled to the temperature of the environment inside the freezing chamber to the inside of the freezing chamber to avoid damage to the low-temperature environment inside the freezing chamber, and the injection of cold dry air can also provide an air medium for the flow of moisture inside the freezing chamber, promote the uniform distribution of the humidity environment inside the freezing chamber, and thus ensure the efficiency of the high-humidity gas exhausted by the negative pressure generated by the air extraction pump 72, promote the freezing and drying process inside the freezing chamber, and the setting of the one-way air valve 73 avoids backflow of the extracted gas, and the moisture in the humid cold air output by the freezing chamber condenses and enters the liquid collection tank 74 during the process of restoring the low-temperature air to normal temperature. Example Four

[0049] Please refer to Figures 1-11 The difference from the above-mentioned embodiments is that a plurality of material scraping mechanisms 8 are further arranged inside the freezing chamber, each material scraping mechanism 8 is arranged above the cooling support plate 3, and the bottom end of the heat conduction plate body 31 of each cooling support plate 3 is provided with a condensation baffle 34; the height of the condensation baffle 34 near one end of the heat preservation cabinet door 2 is higher than the height far from the heat preservation cabinet door 2, and the depth of the cooling tray 4 near one end of the heat preservation cabinet door 2 is lower than the depth far from the heat preservation cabinet door 2; the material scraping mechanism 8 can scrape the material inside each cooling tray 4 to the end near the heat preservation cabinet door 2 after the completion of the freezing and drying, and simultaneously scrape the ice crystals condensed at the bottom end of the condensation baffle 34 to the end far from the heat preservation cabinet door 2.

[0050] The material scraping mechanism 8 comprises a material scraping mounting bracket 81, an upper layer scraping plate 82 and a lower layer scraping plate 83; the upper layer scraping plate 82 comprises an upper layer driving rod 821 and an upper layer scraper 822, and the upper layer driving rod 821 and the upper layer scraper 822 are elastically connected through a plurality of upper layer elastic connecting columns 823; the lower layer scraping plate 83 comprises a lower layer driving rod 831 and a lower layer scraper 832, and the lower layer driving rod 831 and the lower layer scraper 832 are elastically connected through a plurality of lower layer elastic connecting columns 833; the material scraping mounting bracket 81 is provided with an upper layer guide slot 811 and a lower layer guide slot 812, and the upper layer driving rod 821 and the lower layer driving rod 831 respectively penetrate the upper layer guide slot 811 and the lower layer guide slot 812.

[0051] The scraping installation support 81 is provided with a scraping drive sprocket 84, a plurality of upper support sprockets 85 and a plurality of lower support sprockets 86 on one side, the scraping drive sprocket 84 and the plurality of upper support sprockets 85 are externally sleeved with an upper drive chain 87, and the scraping drive sprocket 84 and the plurality of lower support sprockets 86 are externally sleeved with a lower drive chain 88; the upper drive chain 87 is fixed between one end of the upper layer drive rod 821, and the lower drive chain 88 is fixed with one end of the lower layer drive rod 831; the structure shell 11 is internally provided with a scraping drive mechanism 9 outside the heat preservation shell 12, the scraping drive mechanism 9 comprises a plurality of scraping drive units 91, and each scraping mechanism 8 located at the same layer is driven by the same scraping drive unit 91; the scraping drive unit 91 comprises a scraping drive motor 911 and a scraping drive shaft 912, the scraping drive motor 911 is power transmission between the scraping drive shaft 912 through the speed reducer, and the scraping drive shaft 912 and each scraping drive sprocket 84 located at the same layer are coaxially fixed.

[0052] In specific use, after the freeze-drying is completed, in order to avoid that the moisture enters the inside of the cooling tray 4 due to the temperature rise of the moisture condensed on the condensation baffle 34 caused by the opening of the heat preservation cabinet door 2, through the setting of the scraping mechanism 8 and the scraping drive mechanism 9, each scraping drive motor 911 drives the scraping drive shaft 912 to drive each scraping drive sprocket 84 located at the same layer to rotate, and drives the upper drive chain 87 and the lower drive chain 88 to move in opposite directions, and then drives the upper layer drive rod 821 and the lower layer drive rod 831 to move in opposite directions, specifically, the upper layer drive rod 821 moves the upper layer scraper 822 away from one end of the heat preservation cabinet door 2 through each upper layer elastic connecting column 823 under the limitation of the upper layer guide groove 811, and the lower layer drive rod 831 moves the lower layer scraper 832 towards one end close to the heat preservation cabinet door 2 through each lower layer elastic connecting column 833 under the limitation of the lower layer guide groove 812, and then the ice crystals condensed at the bottom end of the condensation baffle 34 can be scraped towards one end away from the heat preservation cabinet door 2, and the dried materials can be scraped towards one end close to the heat preservation cabinet door 2, and the materials can be scraped and collected towards one end close to the heat preservation cabinet door 2, so as to improve the efficiency of collecting the dried materials.

[0053] And in specific use, the upper scraper 822 far from the side of the heat preservation cabinet door 2 can be provided with an inclined baffle, and the scraped ice crystals are guided to the inner wall of the heat preservation shell 12 through the guidance of the inclined baffle, and a collection box is arranged at the bottom end of the heat preservation shell 12 to collect the scraped ice crystals; in specific use, since the height of the condensation baffle 34 close to the end of the heat preservation cabinet door 2 is higher than the height far from the end of the heat preservation cabinet door 2, the scraped ice crystals can be fully collected after falling on the inclined baffle arranged on one side of the upper scraper 822, the depth of the cooling tray 4 close to the end of the heat preservation cabinet door 2 is lower than the depth far from the end of the heat preservation cabinet door 2, so that the materials accumulated due to scraping do not overflow from the side wall of the cooling tray 4, and the elasticity of the upper elastic connecting column 823 and the lower elastic connecting column 833 ensures the abutment between the upper scraper 822 and the lower scraper 832 and the condensation baffle 34 and the cooling tray 4 respectively, so as to ensure the scraping effect of the ice crystals and the dried materials. Example five:

[0054] A preparation process of stevia rebaudiana and chrysanthemum morifolium freeze-dried powder, characterized in that a freeze-drying machine as described in any one of examples one to four is used to freeze-dry stevia rebaudiana and chrysanthemum morifolium concentrated solution, comprising the following steps:

[0055] S. rebaudiana and C. morifolium powders are weighed and extracted in water to obtain stevia rebaudiana and chrysanthemum morifolium extract;

[0056] The S. rebaudiana and C. morifolium powders are dried in an electric heating constant temperature drying oven at 60°C, respectively crushed, and then passed through 40-mesh and 90-mesh sieves to obtain the powders.

[0057] The S. rebaudiana and C. morifolium powders are weighed in a beaker, the ratio of the S. rebaudiana and C. morifolium powders is 0.1-0.5g:4-6g, 10-30 times the amount of water is added, and the mixture is placed in a water bath and extracted at 60-100°C for 20-60 min. The stevia rebaudiana and chrysanthemum morifolium extract is prepared by hot suction filtration, and the extraction is performed 1-3 times.

[0058] In this example, the ratio of the S. rebaudiana and C. morifolium powders is 0.1g:6g, the amount of water added is 20 times, the extraction temperature is 80°C, the extraction time is 40 min, and the extraction is performed 1 time.

[0059] The obtained stevia rebaudiana and chrysanthemum morifolium extract is concentrated to obtain stevia rebaudiana and chrysanthemum morifolium concentrated solution.

[0060] In this example, the stevia rebaudiana and chrysanthemum morifolium extract is concentrated by rotary evaporation, and the concentration ratio is 1:5.

[0061] The stevia rebaudiana and chrysanthemum morifolium concentrated solution is placed in the cooling tray (4) in a certain amount, and each cooling tray (4) is placed in the freezing cavity for freeze-drying to obtain stevia rebaudiana and chrysanthemum morifolium freeze-dried powder.

[0062] In this embodiment, the internal parameters of the freezing cavity are set as temperature -40℃, constant state vacuum degree 0.025MPa, and freeze-drying time 72h.

[0063] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely divergences of the principles and spirit of the application and that numerous modifications, changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A freeze dryer, comprising a freezer chamber, the freezer chamber including a structural shell and an insulated shell, wherein an insulated door is provided on the front of the freezer chamber, and the insulated door, when closed, together with the insulated shell, forms a closed freezer cavity, characterized in that: The freezing chamber is equipped with several cooling support plates. Each pair of adjacent cooling support plates can accommodate a cooling tray, which is used to hold the freeze-dried raw materials. The freezer body is equipped with a compression refrigeration mechanism, an airflow cooling mechanism, and a negative pressure suction mechanism. The compression refrigeration mechanism can provide refrigerant to each of the cooling support plates and the airflow cooling mechanism. The negative pressure suction mechanism can suck up the gas inside the freezer chamber to maintain the negative pressure environment of the freezer chamber. The airflow cooling mechanism can draw in outside air and cool it with the refrigerant provided by the compression refrigeration mechanism before injecting it into the freezing chamber. It also works in conjunction with the suction action of the negative pressure suction mechanism to promote the discharge of high-humidity gas inside the freezing chamber. The cooling support plate includes a heat-conducting plate body, and the compression refrigeration mechanism includes a refrigerant output pipe and a refrigerant recovery pipe. The refrigerant output pipe is connected to the refrigeration heat exchange pipe and the airflow heat exchange pipe respectively through a distribution valve. The end of the refrigeration heat exchange tube that extends into the insulation shell is provided with an input connector, the end of the refrigerant recovery tube that extends into the insulation shell is provided with a return connector, and the airflow heat exchange tube is connected to the refrigerant recovery tube after passing through the airflow cooling mechanism. A heat-conducting coil is provided at the bottom end of the heat-conducting plate, and the wall of the heat-conducting coil is in contact with the heat-conducting plate for heat transfer. The two ends of the heat-conducting coil are connected to the input connector and the return connector respectively, and each of the cooling support plates can be moved out of the freezer cavity as a whole; When neither end of the heat-conducting coil is connected to the input connector and the return connector, both the input connector and the return connector are closed. The top of the heat-conducting plate is provided with an elastic clamping track, and the bottom of the cooling tray is provided with a conductive slider. The thickness of the conductive slider is less than the depth of the elastic clamping track, and the end of the elastic clamping track near the door of the heat preservation cabinet has an expansion opening. The elastic clamping track includes symmetrically arranged elastic clamps, the bottom end of which is welded and fixed to the heat-conducting plate body, and the elastic clamps are capable of deformation; When the conductive slider slides into the elastic clamping track, both elastic clamps can be tightly attached to the conductive slider; The freezing chamber is also equipped with several scraping mechanisms, each of which is located above the cooling support plate. Each of the cooling support plates has a condensation baffle at the bottom of its heat-conducting plate. The height of the condensation baffle near the door of the heat preservation cabinet is higher than the height of the end away from the door of the heat preservation cabinet, and the depth of the cooling tray near the door of the heat preservation cabinet is lower than the depth of the end away from the door of the heat preservation cabinet. The scraping mechanism can scrape the material inside each cooling tray to one end near the door of the insulated cabinet after freeze-drying, and at the same time scrape the ice crystals condensed at the bottom of the condensation baffle to one end away from the door of the insulated cabinet. The scraping mechanism includes a scraping mounting bracket, an upper scraper, and a lower scraper. The upper scraper includes an upper drive rod and an upper scraper blade, which are elastically connected by a plurality of upper elastic connecting columns. The lower scraper includes a lower drive rod and a lower scraper blade, which are elastically connected by a plurality of lower elastic connecting columns. The scraper mounting bracket has an upper guide groove and a lower guide groove, and the upper drive rod and the lower drive rod respectively pass through the upper guide groove and the lower guide groove.

2. The freeze dryer according to claim 1, characterized in that: The airflow cooling mechanism includes an airflow heat exchanger, and an airflow inlet is provided on one side of the airflow heat exchanger. The airflow inlet is connected to the interior of the freezing chamber through an airflow input pipe. Both the airflow inlet pipe and the airflow heat exchange pipe pass through the airflow heat exchanger, and the gas inside the airflow inlet pipe exchanges heat with the refrigerant inside the airflow heat exchange pipe inside the airflow heat exchanger. The airflow inlet pipe is also connected to a booster pump, which provides the power to transport airflow from the airflow inlet into the freezing chamber.

3. A freeze dryer according to claim 2, characterized in that: The negative pressure suction mechanism includes a suction pipe and a suction pump. The suction pump is located inside the suction pipe. A one-way valve is provided at one end of the suction pipe that extends into the freezing chamber. The exhaust direction of the one-way valve is from the freezing chamber to the suction pump. A liquid collection tank is installed at the end of the air extraction pipeline away from the freezing chamber. The liquid collection tank is used to collect moisture in the humid cold air output from the freezing chamber.

4. A freeze dryer according to claim 1, characterized in that: The scraper mounting bracket is provided with a scraper drive sprocket, several upper support sprockets and several lower support sprockets on one side. An upper drive chain is sleeved on the outside of the scraper drive sprocket and several upper support sprockets, and a lower drive chain is sleeved on the outside of the scraper drive sprocket and several lower support sprockets. The upper drive chain is fixed to one end of the upper drive rod, and the lower drive chain is fixed to one end of the lower drive rod; Inside the structural shell and outside the insulation shell, a scraping drive mechanism is also provided. The scraping drive mechanism includes several scraping drive units, and each scraping mechanism located on the same layer is driven by the same scraping drive unit. The scraping drive unit includes a scraping drive motor and a scraping drive shaft. The scraping drive motor transmits power to the scraping drive shaft through a reducer. The scraping drive shaft is coaxially fixed with each scraping drive sprocket located on the same layer.

5. A process for preparing freeze-dried Stevia repens powder, characterized in that, Freeze-drying of Stevia repens concentrate using a freeze dryer as described in any one of claims 1-4 includes the following steps: Stevia powder and sedge powder were weighed separately and extracted in water to obtain sedge and stevia extract. The obtained Stevia repens extract was concentrated to obtain Stevia repens concentrate; Stevia repens concentrate was placed in cooling trays in quantitative amounts, and each cooling tray was placed in a freezing chamber for freeze drying to obtain stevia repens freeze-dried powder.

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