High-efficiency freeze dryer combined with liquid nitrogen and mechanical refrigeration

Abstract

This invention relates to the field of freeze dryer technology, specifically to a high-efficiency freeze dryer that combines liquid nitrogen with mechanical refrigeration. It includes a freeze-drying chamber and a cold trap chamber, with a connecting pipe between them. A vacuum tube at the top of the cold trap chamber is directly connected to a heat dissipation chamber containing a condenser, fully utilizing the residual cooling of liquid nitrogen to ensure more stable operation of the single-stage compression refrigeration cycle. A placement shell for reagent tubes is installed on a shelf, and multiple liquid nitrogen spray devices corresponding to the placement shells are arranged on a sliding plate, allowing direct spraying of liquid nitrogen onto the reagent tubes and increasing the freeze-drying rate. A sliding plug is installed inside the liquid nitrogen spray pipe, connected to a cover. The plug can be adjusted to block the reagent tube, allowing the reagent in the tube to be freeze-dried to a specified weight. This freeze dryer is mainly used in laboratory settings, enabling rapid freeze-drying of small batches and significantly improving experimental efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of freeze dryers, and more specifically, to a high-efficiency freeze dryer that combines liquid nitrogen with mechanical refrigeration. Background Technology

[0002] Freeze-drying (lyophilization) technology refers to freezing materials at low temperatures and then sublimating most of the water in the materials through vacuuming, thereby keeping the materials in a dry state and achieving long-term room temperature preservation. The equipment used to perform freeze-drying is a freeze dryer, which is widely used for the freeze-drying preservation of various biological samples, including biomedical products such as pharmaceuticals, bacteria, and blood products, as well as food products such as meat products, milk, and fruits and vegetables.

[0003] A vacuum freeze dryer (freeze dryer for short) consists of two parts: a freeze drying chamber and a cold trap. The freeze drying chamber contains plates and other components, primarily for holding the freeze-dried products; the cold trap contains coils and other components, primarily for refreezing the solvent that has sublimated from the products. The refrigeration system serves two main purposes: providing cooling for the reagents during the freezing process and providing cooling for the cold trap, condensing the sublimated water vapor in the material into ice during drying, thus achieving the effect of dehydration.

[0004] Chinese Patent (CN211503450U) discloses a combined freeze-drying chamber and cold trap mechanism for a freeze dryer. This mechanism rapidly cools the freeze-drying chamber by spraying liquid nitrogen into it, turning the liquid nitrogen into nitrogen gas. Under vacuum, the nitrogen gas enters the cold trap, where it is pre-cooled using residual cooling. Then, the cold trap is dehydrated using refrigeration equipment, achieving the freeze-drying effect of the freeze-drying chamber. However, the above mechanism has problems: after the nitrogen gas enters the cold trap, its temperature remains very low, and it is expelled through a vacuum tube, failing to fully utilize the residual cooling of the nitrogen. Furthermore, since mechanical refrigeration is typically used in the cold trap, its effectiveness is often affected by the heat dissipation at the heat sink, preventing stable operation over extended periods. Additionally, existing freeze dryers are large and have slow freeze-drying speeds, especially in laboratories where smaller, more efficient freeze dryers are often needed. Therefore, to address these technical problems, the applicant has invented a high-efficiency freeze dryer that combines liquid nitrogen and mechanical refrigeration. Summary of the Invention

[0005] The purpose of this invention is to provide a high-efficiency freeze dryer that combines liquid nitrogen with mechanical refrigeration. This freeze dryer makes full use of the residual cooling of liquid nitrogen, enabling the single-stage compression refrigeration cycle to operate more stably. At the same time, this freeze dryer can improve the freeze-drying rate of reagents. In addition, this freeze dryer can also individually adjust the freeze-drying of reagents in each reagent tube, so that the reagents in each reagent tube can be freeze-dried to a specified weight.

[0006] This invention is implemented as follows: a high-efficiency freeze dryer combining liquid nitrogen and mechanical refrigeration includes a freeze-drying chamber and a cold trap chamber. A connecting pipe connects the freeze-drying chamber and the cold trap chamber, and a solenoid valve is installed on the connecting pipe. Multiple fixed rods are installed inside the freeze-drying chamber, and a placement plate and a sliding plate are slidably sleeved on the fixed rods. The sliding plate is located directly above the placement plate. Multiple reagent tube holding devices are installed on the placement plate, and multiple liquid nitrogen spraying structures corresponding one-to-one with the reagent tube holding devices are installed on the sliding plate. A liquid nitrogen filling structure is located at the top of the sliding plate, which is used to fill liquid nitrogen into the multiple liquid nitrogen spraying structures and spray it into the freeze-drying chamber.

[0007] The top of the cold trap housing is equipped with a vacuum tube, and a vacuum pump is mounted on the vacuum tube. A heat exchange box is located at the end of the vacuum tube away from the cold trap housing, and a nitrogen storage box is located at the bottom of the heat exchange box. A heat dissipation box is also provided on the outer wall of the cold trap housing. A compressor and a throttling device are located inside the heat dissipation box. A condenser is located inside the heat exchange box, and an annular evaporator is located inside the cold trap housing. The annular evaporator, condenser, compressor, and throttling device constitute a single-stage compression refrigeration cycle. The single-stage compression refrigeration cycle is filled with R717 refrigerant.

[0008] Multiple heat dissipation holes are provided on the side walls of both the heat dissipation box and the heat exchange box.

[0009] Furthermore, the reagent tube holding device includes a placement plate, multiple placement shells with open tops, a movable base, a spring, and a pressure sensor; the placement plate has two through holes, the same number as the number of placement shells; the top of the placement shell is fixedly connected to the bottom of the placement plate and communicates with the two through holes; the pressure sensor is fixedly embedded in the bottom inner side of the placement shell; the bottom of the spring is fixedly connected to the pressure sensor; the top of the spring is fixedly connected to the bottom of the movable base; the movable base is slidably connected to the placement shell.

[0010] Furthermore, the sliding plate has multiple through holes one, the same number as through holes two; the liquid nitrogen spraying structure includes a liquid nitrogen spraying pipe, a plug head, a limiting ring, a connecting rod, a cover, and a lifting device; the top of the liquid nitrogen spraying pipe is fixedly connected to the bottom of the sliding plate and communicates with through holes one; the plug head is slidably disposed inside the liquid nitrogen spraying pipe, and the plug head has through holes two along its sliding direction; the limiting ring is fixedly installed on the inner side wall of the liquid nitrogen spraying pipe and located directly above the plug head; the connecting rod is fixedly installed inside through holes two, the bottom of the connecting rod is fixedly connected to a connecting bracket, and the top of the connecting rod passes through the limiting ring and is fixedly connected to the cover, the covering area of ​​the cover being larger than the through hole area of ​​the limiting ring; the lifting device is fixedly installed on the outer side wall of the liquid nitrogen spraying pipe, and the lifting device is used to control the plug head to slide up and down along the liquid nitrogen spraying pipe.

[0011] Furthermore, the lifting device includes a servo motor, a lifting ring, and a second threaded rod; the side wall of the servo motor is fixedly connected to the side wall of the liquid nitrogen spray pipe, the output end of the servo motor is fixedly connected to the top of the second threaded rod, the lifting ring is sleeved on the second threaded rod, and the side wall of the lifting ring is fixedly connected to the side wall of the plug head.

[0012] Furthermore, the plug head is also equipped with a flow regulating valve.

[0013] Furthermore, the liquid nitrogen filling structure includes two liquid nitrogen filling pipes and a distribution box; the two liquid nitrogen filling pipes are detachably connected, and the end of one of the liquid nitrogen filling pipes is fixedly connected to the side wall of the distribution box. The distribution box is fixedly installed on the top of the sliding plate, and the bottom of the distribution box has multiple through holes three corresponding to through hole one.

[0014] Furthermore, both the sliding plate and the shelf are provided with connecting housings on their side walls, and the connecting housings contain rotating fixing structures; the shelf and the sliding plate are provided with grooves communicating with the connecting housings; the rotating fixing structure includes two fixing devices and a transmission device; the fixing device includes a slider, a threaded rod, a knob, and a bevel gear; the slider slides along the groove and is sleeved on the threaded section of the threaded rod, and the end of the smooth section of the threaded rod is rotatably connected to the connecting housing; the transmission device includes two bevel gears, two bevel gears, a transmission rod, and multiple support bearings; the two bevel gears are respectively fixedly sleeved on the threaded sections of the two threaded rods, and the two bevel gears mesh with the two bevel gears; the two bevel gears are respectively fixedly connected to both ends of the transmission rod; the multiple support bearings are fixedly sleeved on the transmission rod; the threaded rod of one of the fixing devices passes through the connecting housing and is provided with a knob.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Connect the end of the vacuum tube furthest from the cold trap box to the heat exchange box, and install the condenser of the single-stage compression refrigeration inside the heat exchange box. In this way, the residual cooling of nitrogen is used to cool the condenser, which improves the refrigeration effect and refrigeration stability of the single-stage compression refrigeration cycle.

[0017] 2. A liquid nitrogen spray structure is installed directly above each housing, and a flow regulating valve is installed on each plug head. This can control the liquid nitrogen injection rate, which can not only quickly freeze-dry the reagent in a single reagent tube, but also avoid the phenomenon of reagent splashing out of the reagent tube due to excessive flow.

[0018] 3. Connect the plug head and the cover with a connecting rod, with the cover and plug head located on opposite sides of the limiting ring. Simultaneously, control the up-and-down movement of the plug head using a lifting device. When the reagent in a single reagent tube reaches the specified weight after lyophilization, the plug head can be adjusted to move downwards to plug the reagent tube. At the same time, the cover seals the hollow part of the limiting ring, which not only prevents liquid nitrogen sprayed from other plug heads from affecting the reagent in the reagent tube, but also plugs the liquid nitrogen spray pipe, preventing liquid nitrogen from continuously being injected into the reagent tube, thus preventing the reagent in the reagent tube from decreasing.

[0019] 4. A spring is installed at the bottom of the movable base, and the bottom of the spring is connected to a pressure sensor. This way, when the reagent is freeze-dried to a specified weight, the freeze-drying of the reagent in that reagent tube can be stopped, achieving the effect of precise freeze-drying control for each reagent tube.

[0020] 5. A rotating fixing structure is provided inside the connecting housing. The rotating fixing structure fixes the shelf and the sliding plate by setting a slider in the slide groove and adjusting the slider to press against the fixing rod. At the same time, the height of the shelf and the sliding plate can also be adjusted.

[0021] 6. Fit both the placement plate and the sliding plate onto the fixed rod, and connect the two hydraulic filling tubes with a rotary joint. This modular design allows the experimenter to replace the placement plate and sliding plate according to the actual size and quantity of the reagent tubes. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a high-efficiency freeze dryer that combines liquid nitrogen and mechanical refrigeration, provided in an embodiment of the present invention;

[0023] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0024] Figure 3 yes Figure 1 Enlarged view of point B in the middle;

[0025] Figure 4 yes Figure 1 Enlarged view of point C in the middle;

[0026] Figure 5 yes Figure 2 Cross-sectional view at point AA;

[0027] Figure 6 This is a top view of a cross-sectional view of the diversion box provided in an embodiment of the present invention;

[0028] Figure 7 This is a side view of the cold trap enclosure provided in an embodiment of the present invention.

[0029] Reference numerals used in the above figures:

[0030] 1. Freeze-drying chamber; 2. Liquid nitrogen filling pipe; 3. Rotary joint; 4. Sliding plate; 5. Shelf plate; 6. Through hole two; 7. Fixing rod; 8. Support frame; 9. Return pipe; 10. Heat dissipation hole; 11. Heat dissipation box; 12. Annular evaporator; 13. Vacuum tube; 14. Cold trap box; 15. Solenoid valve; 16. Connecting pipe; 17. Reagent tube; 18. Through hole one; 19. Diverter box; 20. Slide groove; 21. Sliding block; 22. Bevel gear one; 23. Bevel gear two; 24. Knob; 25. Connecting shell; 26. Threaded rod one; 27. Cover; 28. Limiting ring; 29. ​​Liquid nitrogen spray pipe; 30. Flow regulating valve; 31. Plug head; 32. Through hole four; 33. Threaded rod two; 34. Lifting ring; 35. Servo motor; 36. Connecting bracket; 37. Connecting rod; 38. Heat exchange box; 39. Housing; 40. Pressure sensor; 41. Spring; 42. Movable base; 43. Transmission rod; 44. Support bearing; 45. Through hole three; 46. Liquid inlet branch pipe; 47. Condenser; 48. Flow divider; 49. Throttling device; 50. Compressor; 51. Nitrogen storage tank; 52. Vacuum pump. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] The implementation of the present invention will be described in detail below with reference to specific embodiments.

[0033] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0034] Reference Figure 1-7 The image shown is a preferred embodiment of the present invention.

[0035] A high-efficiency freeze dryer combining liquid nitrogen and mechanical refrigeration includes a freeze-drying chamber 1 and a cold trap housing 14. A connecting pipe 16 connects the freeze-drying chamber 1 and the cold trap housing 14, and a solenoid valve 15 is installed on the connecting pipe 16. Four fixing rods 7 are fixedly installed inside the freeze-drying chamber 1. A placement plate 5 and a sliding plate 4 are simultaneously slidably sleeved on the four fixing rods 7, with the sliding plate 4 located directly above the placement plate 5. Multiple reagent tube 17 holding devices are installed on the placement plate 5, and multiple liquid nitrogen spraying structures corresponding one-to-one with the reagent tube 17 holding devices are installed on the sliding plate 4. A liquid nitrogen filling structure is fixedly installed on the top of the sliding plate 4, which is used to fill liquid nitrogen into the multiple liquid nitrogen spraying structures and spray it into the freeze-drying chamber 1 through the liquid nitrogen spraying structures.

[0036] A vacuum tube 13 is fixedly installed on the top of the cold trap housing 14, and a vacuum pump 52 is installed on the vacuum tube 13. A heat exchange box 38 is installed at the end of the vacuum tube 13 away from the cold trap housing 14. In this embodiment, the heat exchange box 38 is fixedly installed on the outer wall of the cold trap housing 14. A nitrogen storage box 51 is provided at the bottom of the heat exchange box 38 for collecting nitrogen. A heat dissipation box 11 is also fixedly installed on the outer wall of the cold trap housing 14. A compressor 50 and a throttling device 49 are fixedly installed inside the heat dissipation box 11. A condenser 47 is installed inside the heat exchange box 38, and an annular evaporator 12 is installed inside the cold trap housing 14. The annular evaporator 12, condenser 47, compressor 50, and throttling device 49 form a single-stage compression refrigeration cycle; the single-stage compression refrigeration cycle is filled with R717 refrigerant; in this embodiment, there are two annular evaporators 12, located on the upper and lower sides of the connecting pipe 16 respectively; the liquid outlets of the two annular evaporators 12 are simultaneously connected to the return liquid pipe 9, which is then connected to the inlet of the compressor 50; a distributor 48 is connected to the liquid outlet of the throttling device 49, and the distributor 48 is connected to two inlet branch pipes 46 respectively, which are connected to the two annular evaporators 12 respectively.

[0037] Multiple heat dissipation holes 10 are provided on the side walls of both the heat dissipation box 11 and the heat exchange box 38. In this embodiment, support frames 8 are installed at the bottom of both the cold trap box 14 and the freeze-drying chamber 1.

[0038] In this preferred embodiment, the reagent tube 17 holding device includes a placement plate 5, multiple placement housings 39 with open tops, a movable base 42, a spring 41, and a pressure sensor 40; the placement plate 5 has the same number of through holes 6 as the placement housings 39, and the placement plate 5 can be any one of a 24-well plate, a 48-well plate, or a 96-well plate; the top of the placement housing 39 is fixedly connected to the bottom of the placement plate 5 and communicates with the through holes 6; Figure 4As shown, the pressure sensor 40 is fixedly embedded in the bottom inner side of the housing 39, the bottom of the spring 41 is fixedly connected to the pressure sensor 40, and the top of the spring 41 is fixedly connected to the bottom of the movable base 42; the movable base 42 is slidably connected to the housing 39. In order to better place the reagent tube 17, the top of the movable base 42 in this embodiment is arc-shaped. The reagent tube 17 is placed on the movable base 42. During the freeze-drying process, the mass of the reagent tube 17 decreases. When the pressure sensor 40 senses the weight change to a specified value, it stops the freeze-drying of the reagent in the reagent tube 17.

[0039] In this preferred embodiment, the sliding plate 4 has a plurality of through holes 18, the same number as the through holes 2 6; the liquid nitrogen spray structure includes a liquid nitrogen spray pipe 29, a plug head 31, a limiting ring 28, a connecting rod 37, a baffle 27, and a lifting device; the top of the liquid nitrogen spray pipe 29 is fixedly connected to the bottom of the sliding plate 4 and communicates with the through holes 18; Figure 3 As shown, the plug head 31 is slidably disposed inside the liquid nitrogen spray pipe 29. The diameter of the plug head 31 matches the inner diameter of the reagent tube 17. The plug head 31 can seal the reagent tube 17 when inserted into it. A through hole 32 along its length is opened inside the plug head 31. The limiting ring 28 is fixedly installed on the inner side wall of the liquid nitrogen spray pipe 29 and located directly above the plug head 31. The connecting rod 37 is fixedly installed inside the through hole 32. The bottom of the connecting rod 37 is fixedly connected to the connecting bracket 36, and the top of the connecting rod 37 passes through the limiting ring 28 and is fixedly connected to the cover 27. The covering area of ​​the cover 27 is larger than the through hole area of ​​the limiting ring 28. The lifting device is fixedly installed on the outer side wall of the liquid nitrogen spray pipe 29. The lifting device is used to control the plug head 31 to slide up and down along the liquid nitrogen spray pipe 29. In this embodiment, in order to reduce the local resistance loss of liquid nitrogen flow, the top of the plug head 31 is set as a flared structure, and the top of the limiting ring 28 is also set as a top flared structure.

[0040] In this preferred embodiment, the lifting device includes a servo motor 35, a lifting ring 34, and a threaded rod 33. The side wall of the servo motor 35 is fixedly connected to the side wall of the liquid nitrogen spray pipe 29, and the output end of the servo motor 35 is fixedly connected to the top of the threaded rod 33. The lifting ring 34 is sleeved on the threaded rod 33, and the side wall of the lifting ring 34 is fixedly connected to the side wall of the plugging head 31. When the servo motor 35 drives the threaded rod 33 to rotate, the lifting ring 34 and the plugging head 31 move up and down synchronously because the lifting ring 34 is sleeved on the threaded rod 33.

[0041] In this preferred embodiment, the plug head 31 is also equipped with a flow regulating valve 30, which can reduce the injection rate of liquid nitrogen and prevent the reagent from splashing out of the reagent tube 17 during the freeze-drying process.

[0042] In this preferred embodiment, the liquid nitrogen filling structure includes two liquid nitrogen filling pipes 2 and a distribution box 19; the two liquid nitrogen filling pipes 2 are detachably connected by a rotary joint 3, and the end of one of the liquid nitrogen filling pipes 2 is fixedly connected to the side wall of the distribution box 19. The distribution box 19 is fixedly installed on the top of the sliding plate 4, and the bottom of the distribution box 19 has multiple through holes 45 corresponding to the through holes 18, so that the sliding plate 4 and the shelf 5 with different numbers of through holes can be removed from the fixing rod 7.

[0043] In this preferred embodiment, such as Figure 5 As shown, both the sliding plate 4 and the shelf 5 have connecting housings 25 on their side walls, and the connecting housings 25 have rotating fixing structures inside. The shelf 5 and the sliding plate 4 have grooves 20 communicating with the connecting housings 25. The rotating fixing structure includes two fixing devices and a transmission device. The fixing devices include a slider 21, a threaded rod 26, a knob 24, and a bevel gear 22. The slider 21 slides along the groove 20 and is fitted onto the threaded section of the threaded rod 26. The smooth end of the threaded rod 26 is connected to the connecting housing 25 by a bearing. The transmission device includes two bevel gears 22, two bevel gears 23, and a transmission mechanism. The transmission rod 43 and multiple support bearings 44 are provided; two bevel gears 22 are respectively fixedly sleeved on the threaded sections of two threaded rods 26, and two bevel gears 23 are respectively meshed with the two bevel gears 22; the two bevel gears 23 are respectively fixedly connected to both ends of the transmission rod 43; multiple support bearings 44 are fixedly sleeved on the transmission rod 43; one of the threaded rods 26 of the fixing device passes through the connecting housing 25 and is fixedly installed with a knob 24; the purpose of the transmission device is to enable the two sliders 21 to move simultaneously toward the fixing rod 7 and press against it when the knob 24 is rotated, so as to fix the placement plate 5 and the sliding plate 4.

[0044] Working principle: During the freeze-drying process, the placement plate 5 is adjusted to the designated height and fixed. Then, liquid nitrogen is added to the distribution box 19, flowing evenly into different through holes 45, and then into the liquid nitrogen spray pipe 29; it is sprayed out through the through hole 32 in the plug head 31, achieving rapid freezing of the reagent to below the triple point temperature. At the same time, the controller opens the solenoid valve 15, and the vacuum pump 52 evacuates the inside of the cold trap box 14. Simultaneously, the annular evaporator 12 of the single-stage compression refrigeration system provides the required cooling capacity to the cold trap box 14, causing water vapor to condense into water. To achieve the freeze-drying effect, liquid nitrogen absorbs a large amount of heat and turns into nitrogen gas, which enters the cold trap chamber 14 and then the heat exchange chamber 38 to exchange heat with the condenser 47 through convection, thus lowering the temperature of the condenser 47. During this process, the water in the reagent forms solid ice crystals under the action of liquid nitrogen, reducing microbial activity and chemical reactions. When the vacuum pump 52 draws a vacuum, the pressure in the freeze-drying chamber 1 is reduced, causing the solid ice crystals to directly transform into water vapor, bypassing the liquid state. Finally, the water gradually sublimates through the annular evaporator 12 of the cold trap chamber 14 and is then extracted. During the freeze-drying process, the weight of the reagent in the reagent tube 17 decreases. When the specified weight is reached, the controller adjusts the servo motor 35 to drive the threaded rod 33 to rotate. When the plug 31 is inserted into the opening of the reagent tube 17, the cover 27 simultaneously closes with the top of the limiting ring 28. This not only prevents the liquid nitrogen sprayed from other plugs 31 from affecting the reagent in the reagent tube 17, but also blocks the liquid nitrogen spray pipe 29 to prevent liquid nitrogen from being sprayed into the reagent tube 17.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-efficiency freeze dryer that combines liquid nitrogen with mechanical refrigeration, characterized in that, The system includes a freeze-drying chamber (1) and a cold trap housing (14). A connecting pipe (16) is provided between the freeze-drying chamber (1) and the cold trap housing (14) to connect them. A solenoid valve (15) is provided on the connecting pipe (16). Multiple fixed rods (7) are provided inside the freeze-drying chamber (1). A placement plate (5) and a sliding plate (4) are slidably sleeved on the multiple fixed rods (7). The sliding plate (4) is located directly above the placement plate (5). Multiple reagent tube (17) holding devices are provided on the placement plate (5). Multiple liquid nitrogen spraying structures are provided on the sliding plate (4) corresponding to the reagent tube (17) holding devices. A liquid nitrogen filling structure is provided on the top of the sliding plate (4). The liquid nitrogen filling structure is used to fill liquid nitrogen into the multiple liquid nitrogen spraying structures and spray it into the freeze-drying chamber (1) through the liquid nitrogen spraying structures. The top of the cold trap housing (14) is provided with a vacuum tube (13), and a vacuum pump (52) is provided on the vacuum tube (13). A heat exchange box (38) is provided at the end of the vacuum tube (13) away from the cold trap housing (14), and a nitrogen storage box (51) is provided at the bottom of the heat exchange box (38). A heat dissipation box (11) is also provided on the outer wall of the cold trap housing (14). A compressor (50) and a throttling device (49) are provided in the heat dissipation box (11). A condenser (47) is provided in the heat exchange box (38), and an annular evaporator (12) is provided in the cold trap housing (14). The annular evaporator (12), condenser (47), compressor (50) and throttling device (49) form a single-stage compression refrigeration cycle. The single-stage compression refrigeration cycle is filled with R717 refrigerant. Multiple heat dissipation holes (10) are opened on the side walls of the heat dissipation box (11) and the heat exchange box (38); The reagent tube (17) holding device includes a placement plate (5), multiple placement shells (39) with open tops, a movable base (42), a spring (41), and a pressure sensor (40); the placement plate (5) has the same number of through holes (6) as the placement shells (39), the top of the placement shells (39) is fixedly connected to the bottom of the placement plate (5) and communicates with the through holes (6); the pressure sensor (40) is fixedly embedded in the inner bottom of the placement shells (39), the bottom of the spring (41) is fixedly connected to the pressure sensor (40), and the top of the spring (41) is fixedly connected to the bottom of the movable base (42); the movable base (42) is slidably connected to the placement shells (39); The sliding plate (4) has multiple through holes (18) of the same number as through holes (2) (6); the liquid nitrogen spray structure includes a liquid nitrogen spray pipe (29), a plug head (31), a limiting ring (28), a connecting rod (37), a cover (27), and a lifting device; the top of the liquid nitrogen spray pipe (29) is fixedly connected to the bottom of the sliding plate (4) and communicates with through holes (18); the plug head (31) is slidably disposed in the liquid nitrogen spray pipe (29), and the plug head (31) has through holes (4) (32) along its sliding direction; the limiting ring (28) is fixedly installed in the liquid nitrogen spray pipe (6). The nitrogen spray pipe (29) is located on the inner wall and directly above the plug head (31); the connecting rod (37) is fixedly installed in the through hole four (32), the bottom of the connecting rod (37) is fixedly connected to the connecting bracket (36), the top of the connecting rod (37) passes through the limiting ring (28) and is fixedly connected to the cover (27), the covering area of ​​the cover (27) is larger than the through hole area of ​​the limiting ring (28); the lifting device is fixedly installed on the outer wall of the liquid nitrogen spray pipe (29), and the lifting device is used to control the plug head (31) to slide up and down along the liquid nitrogen spray pipe (29).

2. The high-efficiency freeze dryer using a combination of liquid nitrogen and mechanical refrigeration as described in claim 1, characterized in that, The lifting device includes a servo motor (35), a lifting ring (34), and a threaded rod (33); the side wall of the servo motor (35) is fixedly connected to the side wall of the liquid nitrogen spray pipe (29), the output end of the servo motor (35) is fixedly connected to the top of the threaded rod (33), the lifting ring (34) is sleeved on the threaded rod (33), and the side wall of the lifting ring (34) is fixedly connected to the side wall of the plug head (31).

3. The high-efficiency freeze dryer using a combination of liquid nitrogen and mechanical refrigeration according to claim 1, characterized in that, The plug head (31) is also equipped with a flow regulating valve (30).

4. The high-efficiency freeze dryer using a combination of liquid nitrogen and mechanical refrigeration according to claim 1, characterized in that, The liquid nitrogen filling structure includes two liquid nitrogen filling pipes (2) and a diversion box (19); the two liquid nitrogen filling pipes (2) are detachably connected, and the end of one liquid nitrogen filling pipe (2) is fixedly connected to the side wall of the diversion box (19). The diversion box (19) is fixedly installed on the top of the sliding plate (4), and the bottom of the diversion box (19) has multiple through holes (45) corresponding to through hole one (18).

5. A high-efficiency freeze dryer combining liquid nitrogen and mechanical refrigeration according to claim 1, characterized in that, Both the sliding plate (4) and the shelf (5) are provided with connecting housings (25), and the connecting housings (25) are provided with rotating fixing structures. The shelf (5) and the sliding plate (4) are provided with sliding grooves (20) that communicate with the connecting housings (25). The rotating fixing structure includes two fixing devices and a transmission device. The fixing devices include a slider (21), a threaded rod (26), a knob (24), and a bevel gear (22). The slider (21) slides along the sliding groove (20) and is sleeved on the threaded section of the threaded rod (26). The end of the smooth section of the threaded rod (26) rotates with the connecting housing (25). The transmission device includes two bevel gears (22), two bevel gears (23), a transmission rod (43), and multiple support bearings (44). The two bevel gears (22) are respectively fixedly sleeved on the threaded sections of the two threaded rods (26), and the two bevel gears (23) respectively mesh with the two bevel gears (22). The two bevel gears (23) are respectively fixedly connected to both ends of the transmission rod (43). The multiple support bearings (44) are fixedly sleeved on the transmission rod (43). The threaded rod (26) of one of the fixing devices passes through the connecting housing (25) and is provided with a knob (24).

Images