A vacuum microwave low-temperature drying apparatus

Abstract

This utility model discloses a vacuum microwave low-temperature drying device, comprising: a horizontal cylindrical body with its inner cavity serving as a vacuum drying chamber; a dual-axis auger system housed within the vacuum drying chamber; the dual-axis auger system having multiple spirally distributed blades arranged at an angle; the dual-axis auger system rotating in opposite directions; a vacuum system including a vacuum pump connected to the vacuum drying chamber via pipelines and an automatic valve; a horizontal cylindrical body with uniformly distributed feed inlets; and a microwave heating module connected to the vacuum drying chamber via these feed inlets; and a PLC control system electrically connected to at least the dual-axis auger system, the vacuum pump, and the microwave heating module, used to regulate the vacuum level, temperature, and stirring speed. This utility model utilizes the angle and reverse convection design of its dual-axis counter-rotating blades to drive the material into a composite cyclic motion in the radial, circumferential, and axial directions, effectively improving the uniformity of material mixing in conjunction with the "instantaneous weightlessness" effect under vacuum conditions.

Description

Technical Field

[0001] This utility model relates to the field of material drying technology, and in particular to a vacuum microwave low-temperature drying equipment suitable for the rapid and uniform low-temperature drying of powder or granular materials in the chemical, plastics, pharmaceutical and food industries. Background Technology

[0002] Existing box-type vacuum microwave heating and drying equipment and continuous belt-type vacuum microwave equipment, in the application of low-temperature rapid drying of powders and solid granular materials, mostly adopt static drying methods. While there are also hanging-style three-dimensional rotary drying methods, these involve the material rotating as a whole without internal tumbling. In the later stages when the material has a low moisture content, due to the rapid microwave heating and insufficient heat dissipation, the temperature difference between the surface, center, and bottom layers of the material can reach several degrees or even tens of degrees Celsius. This leads to problems such as internal overheating, charring, decomposition, and melting, causing irreparable economic losses. To improve these problems, existing equipment can only address them by extending the drying time or lowering the drying temperature, significantly reducing drying efficiency. Therefore, there is an urgent need for equipment and methods that can achieve three-dimensional uniform mixing, rapid low-temperature drying, and preservation of material properties. Summary of the Invention

[0003] To address the aforementioned issues, our company has developed a device and method that combines biaxial gravity-free stirring with vacuum microwave low-temperature drying to achieve rapid and uniform drying of materials, avoid high-temperature damage, and improve efficiency and product quality.

[0004] To solve the above-mentioned technical problems, this utility model provides a vacuum microwave low-temperature drying device, comprising:

[0005] A horizontal cylindrical body, the inner cavity of which is a vacuum drying chamber, the vacuum drying chamber is equipped with a dual-shaft auger system, the dual-shaft auger system is provided with multiple spirally distributed blades, the blades are arranged at an angle to the horizontal plane of their respective phases, and the dual-shaft auger system rotates in opposite directions.

[0006] A vacuum system, including a vacuum pump, which is connected to the vacuum drying chamber via pipelines and automatic valves;

[0007] The microwave heating module has a horizontal cylindrical body with evenly distributed feed inlets, and the microwave heating module is connected to the vacuum drying chamber through the feed inlets;

[0008] The PLC control system is electrically connected to at least the dual-axis auger system, the vacuum pump, and the microwave heating module, and is used to regulate the vacuum level, temperature, and stirring speed.

[0009] Preferably, it also includes a water vapor capture system, which includes a cryogenic refrigerator. The cryogenic refrigerator is connected to a condensing coil and a water trap via an input pipe. The water trap is connected to the horizontal cylinder via a pipeline.

[0010] Preferably, the PLC control system is electrically connected to the water and air capture system.

[0011] Preferably, the blades are spirally arranged on the rotating shaft, and the blades include a shaft. One end of the shaft is connected to the rotating shaft, and the other end is connected to a deflecting blade. The deflecting blade is angled relative to the horizontal plane of its respective phase.

[0012] Preferably, the deflecting blades are respectively configured as one or more rotating blade array groups along the circumference of the rotation axis. Each rotating blade array group includes at least two main deflecting blade groups. The main deflecting blade groups include at least one pair of deflecting blades tilted in opposite directions, and a phase angle is set between the deflecting blades tilted in opposite directions.

[0013] Preferably, the vacuum system includes an automatic material suction structure communicating with the horizontal cylinder, the automatic material suction structure comprising:

[0014] The vacuum feed line is connected to the horizontal cylinder via the automatic valve;

[0015] The PLC control module is configured to control the start and stop of the vacuum pump and the opening and closing of the automatic valve in stages to achieve vacuum gradient adjustment.

[0016] The material filling sensor monitors the material volume inside the horizontal cylinder in real time, and triggers the automatic valve to close when the filling volume reaches 1 / 2-2 / 3.

[0017] Preferably, the horizontal cylindrical body is connected to a sealed discharge structure, the sealed discharge structure comprising:

[0018] A sealed unloading device is connected to the bottom of the horizontal cylinder via a tapered tube;

[0019] The electromagnetic shielded sealing door uses a reducer to drive a lead screw to achieve linear extension and retraction. The surface of the electromagnetic shielded sealing door is covered with lip-shaped silicone seals and an electromagnetic shielding mesh to ensure vacuum sealing and electromagnetic wave shielding during unloading.

[0020] Positive pressure gas is introduced into the vacuum drying chamber of the horizontal cylinder, and drying gas at ≥0.3MPa is introduced to force the discharge of residual material.

[0021] Preferably, the telescopic stroke of the electromagnetic shielding sealing door is 50-100mm, the sealing pressure is ≥0.1MPa, the aperture of the electromagnetic shielding mesh is ≤1mm, and the electromagnetic wave attenuation rate is ≥99%.

[0022] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0023] The dual-axis counter-rotating blades, through angular and reverse convection design, drive the material to form a complex cyclic motion in the radial, circumferential, and axial directions. Combined with the "instantaneous weightlessness" effect in a vacuum environment, this improves the uniformity of material mixing. It also reduces the temperature difference between the inside and outside of the material, avoiding problems such as coking, melting, or component decomposition caused by localized overheating.

[0024] Microwave penetrating heating combined with a vacuum low-pressure environment lowers the boiling point of moisture, allowing for simultaneous heating of the material inside and out, resulting in a higher moisture evaporation rate compared to traditional hot air drying. Simultaneously, the vacuum environment reduces heat convection loss, lowers overall energy consumption, shortens the drying cycle, protects heat-sensitive components, and reduces nutrient loss.

[0025] Reduce overall energy consumption and shorten the drying cycle. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a front view of a vacuum microwave low-temperature drying device according to an embodiment of the present invention;

[0028] Figure 2 Right view of a vacuum microwave low-temperature drying device according to an embodiment of this utility model;

[0029] Figure 3 A schematic diagram of a dual-stirring mechanism transmission structure is shown for a vacuum microwave low-temperature drying device according to an embodiment of this utility model;

[0030] Figure 4 This is a schematic diagram of the material path structure of a vacuum microwave low-temperature drying device according to an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of a low-temperature condensation device is shown for an embodiment of the present invention, illustrating the structure of a vacuum microwave low-temperature drying device.

[0032] Figure 6 for Figure 1 A magnified view of a portion of the central section (I).

[0033] Figure 7 This embodiment presents a schematic diagram of the horizontal cylinder and the dual-shaft auger system.

[0034] Among them, 1 - horizontal cylinder, 2 - dual-shaft auger system, 3 - blade, 4 - microwave heating module, 5 - water vapor capture system, 6 - sealed unloading device, 9 - rotating shaft, 10 - propeller rod, 11 - deflecting blade, 12 - rotating blade array group, 13 - main acting deflecting blade group, 111 - automatic valve, 112 - automatic air intake valve, 113 - unloading valve, 115 - exhaust valve, 116 - vacuum feed pipeline, 117 - water trap, 119 - vacuum pump, 222 - infrared thermometer, 334 - storage tank, 336 - lead screw, 337 - electromagnetic shielding sealing door, 338 - electromagnetic shielding mesh, 339 - drying chamber cavity plate, 341 - conical tube, 344 - reducer, 345 - lip silicone seal, 555 - geared motor, 557 - 558 - Driven gear, 559 - Driven gear, 666 - Cryogenic refrigerator, 667 - Input pipe, 668 - Condensate coil, 669 - Return pipe. Detailed Implementation

[0035] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0036] like Figures 1 to 7 As shown in the figure, this embodiment provides a vacuum microwave low-temperature drying device, and its specific implementation method is as follows.

[0037] The equipment mainly includes a horizontal cylinder 1, a dual-shaft auger system 2, a vacuum feeding system 3, a microwave heating module 4, a water vapor capture system 5, and a sealing unloading device 6. Specifically, the two ends of the horizontal cylinder are connected to the vacuum feeding pipeline 116 and the sealing unloading device 6 respectively via flanges. The vacuum feeding system 3 includes a vacuum pump 119, which is connected to the horizontal cylinder 1 via the vacuum feeding pipeline 116. The pumping speed is 10-50 L / s, the ultimate vacuum degree is ≤-0.1 MPa, and it is controlled by an automatic valve 111. A material filling sensor is installed on the side wall of the horizontal cylinder 1, using ultrasonic or capacitive detection to accurately control the material filling amount to 1 / 2-2 / 3 of the cylinder volume, ensuring sufficient stirring space and avoiding increased energy consumption due to overload. The feed inlets of the microwave heating module 4 are evenly distributed on the top of the horizontal cylinder 1, with a coverage area of ​​≥90%. Microwave penetrating heating causes the material to heat up simultaneously inside and out, reducing temperature differences and preventing surface overheating and coking. An infrared thermometer 222 is installed on the side wall of the horizontal cylinder 1. The infrared thermometer 222 monitors the surface temperature of the material in a non-contact manner with high accuracy. The data is fed back to the PLC system in real time, which controls the microwave power output to ensure that the material temperature is always below the boiling point of water in a vacuum environment, preventing local overheating. The horizontal design reduces the material accumulation height, and the combination with dual-shaft stirring improves the mixing efficiency.

[0038] The horizontal cylinder 1 is equipped with a dual-shaft auger system 2. The two shafts of the dual-shaft auger system 2 are arranged parallel inside the horizontal cylinder 1. They are driven to rotate in opposite directions by a geared motor 555 via a drive gear 557 and a driven gear 559. The rotation speed is controlled by a PLC system. Blades 3 are evenly arranged around the circumference of the dual-shaft auger. The blades 3 are welded to the auger surface at a 25° angle and work in conjunction with the auger's spiral to generate alternating shear forces during rotation. In a vacuum environment, this causes the material to instantly lose weight and drives it to move radially, circumferentially, and axially, forming a three-dimensional flow layer. The geared motor 555 drives the dual-shaft auger to rotate via a chain 558. The angled design of the blades 3 and their counter-rotating characteristics enable the material to achieve "instantaneous weightlessness" mixing within the horizontal cylinder 1. Simultaneously, the microwave heating module 4 radiates energy to the material in the flow layer through the top feed inlet. An infrared thermometer 222 provides real-time temperature feedback to the PLC, dynamically adjusting the microwave power to ensure heating uniformity (temperature difference ≤ 2℃).

[0039] like Figure 7As shown, the dual-axis auger system 2 includes two sets of parallel rotating shafts 9. Each set of rotating shafts 9 has a helically arranged blade 3. Each blade 3 includes a shaft 10, one end of which is connected to the rotating shaft 9, and the other end is connected to a deflecting blade 11. The deflecting blade 11 is angled relative to its connecting shaft 10 in the horizontal plane. When the rotating shaft 9 rotates, the helical shape guides the material along the axial direction of the rotating shaft 9, generating propulsion and causing axial displacement of the material. The deflecting blade 11 is angled relative to the shaft 10 in the horizontal plane. When the blade 3 rotates with the rotating shaft 9, the deflecting blade 11 generates tangential and radial forces on the material during contact. The tangential force propels the material in a circumferential direction, while the radial force causes a positional change in the material along the inner diameter of the cylinder. The multi-directional force exerted on the material by the blades 3 at different positions causes the material to continuously change its direction of motion during the mixing process, forming a complex and interwoven motion trajectory within the horizontal cylinder 1. This further promotes the dispersion and mixing of the material. Compared to ordinary flat blades that can only simply push the material, this design greatly improves the uniformity of mixing and ensures that all parts of the material are fully mixed during the mixing process.

[0040] In other specific embodiments, the deflecting blades 11 are respectively configured as one or more rotating blade array groups 12 along the circumference of the rotation axis 9. Each rotating blade array group 12 includes two groups of main-acting deflecting blade groups 13. Each main-acting deflecting blade group 13 includes a pair of adjacent deflecting blades 11 tilted in opposite directions, with a phase angle set between the adjacent deflecting blades 11 tilted in opposite directions. When the rotation axis 9 rotates, the adjacent and oppositely tilted deflecting blades 11 in the same main-acting deflecting blade group 13 generate opposite tangential forces on the material. For example, one blade pushes the material to the left, while the adjacent oppositely tilted blade pushes the material to the right. This opposite force promotes strong convection and mixing of the material in a local area. Setting the phase angle, such as 90° or 180°, allows different main-acting deflecting blade groups 13 to apply forces to the material at different times. When one group of blades pushes the material to a certain position, after a time interval corresponding to the phase angle, another group of blades applies an opposite force to the material, and the material is pushed back or to another direction.

[0041] In other specific embodiments, the adjacent deflecting blades 11 of the main deflecting blade groups 13 in each group of rotating blade arrays 12 are arranged in a continuous, unidirectional spiral inclination. When the rotating shaft rotates, the adjacent deflecting blades 11 in the same main deflecting blade group 13, which are inclined in opposite directions, generate tangential forces in opposite directions on the material. Due to the unidirectional spiral inclination of the deflecting blades 11 in adjacent array groups, the material smoothly enters the action range of the next main deflecting blade group 13 after leaving the action area of ​​one main deflecting blade group 13, and is continuously subjected to complex and orderly forces, forming a continuous and complex material movement trajectory around the entire circumference of the rotating shaft 9. This design greatly enhances the interaction between materials, allowing the materials to be fully mixed during the stirring process, further improving the stirring uniformity and efficiency.

[0042] In other specific embodiments, the cryogenic refrigerator 666 is connected to the condensing coil 668 inside the water trap 117 via an input pipe 667. The refrigerant circulates within the coil and then returns to the refrigerator for compression via a return pipe 669. The cryogenic condensation rapidly liquefies water vapor, resulting in high trapping efficiency. The temperature can be adjusted below the dew point (e.g., -43℃ corresponds to a moisture content ≤100ppm), meeting ultra-low moisture requirements. The bottom of the water trap 117 is equipped with a drain valve, and the top is connected to the horizontal cylinder 1 via a pipe. When the infrared thermometer 222 detects that the material temperature exceeds the vacuum boiling point, the PLC starts the cryogenic refrigerator 666. The refrigerant at -43℃ enters the condensing coil 668 via the input pipe 667. Water vapor evaporated inside the horizontal cylinder 1 condenses into liquid upon contact with the cryogenic coil and is discharged through the drain valve. A guide plate inside the water trap 117 extends the water vapor path, improving condensation efficiency.

[0043] The sealing unloading device 6 is connected to the bottom of the horizontal cylinder 1 via a tapered tube 341. An electromagnetic shielding sealing door 337 is installed at the outlet end. The sealing door's linear extension and retraction is controlled by a reducer 344 driving a lead screw 336, with a stroke of 50-100 mm and a sealing pressure ≥0.1 MPa. The electromagnetic shielding mesh 338 and the lip-shaped silicone seal 345 provide double protection, ensuring zero microwave leakage during unloading and a vacuum seal ≤0.01 Pa·m³ / s.

[0044] This embodiment also includes a high-pressure gas cleaning pipeline, in which dry gas (nitrogen or dehumidified air) at ≥0.3MPa is introduced, with a pulse frequency of 2-5 times / second. The nozzles are distributed on the inner wall of the horizontal cylinder 1 and in the gap between the blades 3. The pulsed airflow removes residual materials, and the dry gas avoids secondary moisture absorption.

[0045] The drying method in this embodiment includes the following steps:

[0046] Vacuum feeding: Close the automatic valve 111 and the sealing unloading device 6, turn on the vacuum pump 119, and evacuate the vacuum drying chamber of the horizontal cylinder 1 through the pipeline 115. When the set negative pressure value is reached, open the automatic valve 111 to suck the material to be dried into the drying chamber. When the filling amount reaches 1 / 2 to 2 / 3 of the total volume of the vacuum drying chamber, close the automatic valve 111 to complete the feeding process.

[0047] Stirring and Heating: Once the preset vacuum value is reached, the geared motor 555 is turned on, driving the drive gear 557 to rotate. This, in turn, drives the driven gear 559 via the chain 558, causing the dual-shaft auger system 2 to rotate. This, in turn, drives the paddles 3 to create gravity-free stirring of the material. Simultaneously, the microwave heating module 4 is activated to uniformly heat the material. The material itself absorbs electromagnetic wave energy, causing it to heat up rapidly both internally and externally. Staged vacuum control (rapid vacuuming followed by slow feeding) ensures uniform material distribution and a filling error of ≤5%.

[0048] Moisture capture: When the infrared thermometer 222 detects that the preset temperature of the material is higher than the boiling point temperature under the corresponding vacuum, the -43℃ low temperature refrigerator 666 is turned on. At this time, the low temperature refrigerant enters the condenser coil 668 of the water trap 117 through the input pipe 667 to capture the moisture. The cooled refrigerant returns to the compressor of the low temperature refrigerator 666 through the return pipe 669 for refrigeration, and then circulates back to the water trap 117 to capture moisture.

[0049] Vacuum breaking and unloading: After the dried material reaches the set temperature and is kept at that temperature for more than 5 minutes, the microwave heating module 4 is stopped, the vacuum pump 119 is stopped, and the automatic air inlet valve 112 is opened to draw in pre-treated dry air or anhydrous gas, breaking the vacuum in the vacuum drying chamber of the horizontal cylinder 1 to a positive pressure of 5 kPa to 15 kPa. At this time, the sealing unloading device 6 is opened, the unloading valve 113 is opened, and the exhaust valve 115 is opened to exhaust the gas. Under the action of the paddle 3, the material enters the storage tank 334 through the conical tube 341. Positive pressure unloading avoids material blockage; low-speed stirring assists in discharge, significantly improving efficiency.

[0050] Material Cleaning: Under the influence of the paddle 3 and its own gravity, 95% of the material will automatically enter the storage tank 334. At this time, pre-treated dry air or anhydrous gas at ≥0.3MPa is introduced through the automatic air inlet valve 112, forcibly blowing the material below the paddle 3 into the sealed discharge device 6 until the material is completely discharged into the storage tank, ending the entire drying process. Low-Temperature Condensation: According to the required moisture content after drying, the temperature of the low-temperature refrigeration unit 666 is adjusted to correspond to the dew point temperature. For example, if the material needs to have a moisture content below 100ppm after drying, the corresponding temperature should be below -38℃. The actual set temperature of the low-temperature refrigeration unit 666 should be -43℃. Low-temperature condensation avoids water vapor backflow, resulting in smaller fluctuations in the moisture content of the dried material. Electromagnetic shielding and gas sealing in the sealed discharge device 6: Activating the reducer 344 drives the lead screw 336 to rotate, causing the sealing door 337 to extend and retract linearly. When the electromagnetic shielding sealing door 337 extends, the electromagnetic shielding mesh 338 and the drying chamber cavity plate 339 form an electromagnetic shielding seal, and the lip-shaped silicone seal 345 provides a vacuum seal when the lead screw 336 rotates. When the sealing door 337 retracts, it performs an unloading action. Pulse cleaning is time-efficient and leaves minimal residue, meeting the needs of continuous production.

[0051] It should be noted that the "valve" mentioned above includes other automatic valves such as "pneumatic valves" and "electric valves," which are controlled by the PLC to "open" or "close" to cut off or open the air or material path. In this embodiment, they are uniformly referred to as "automatic valves."

[0052] The above description of the embodiments is only for the purpose of helping to understand the present utility model, but does not constitute a limitation of the present utility model. Those skilled in the art can make various changes, modifications, substitutions, integrations and variations without departing from the spirit and scope of the present utility model. Therefore, all equivalent technical solutions should also fall within the scope of the present utility model and should be defined by the claims.

Claims

1. A vacuum microwave low-temperature drying device, characterized in that, include: A horizontal cylindrical body, the inner cavity of which is a vacuum drying chamber, the vacuum drying chamber is equipped with a dual-shaft auger system, the dual-shaft auger system is provided with multiple spirally distributed blades, the blades are arranged at an angle to the horizontal plane of their respective phases, and the dual-shaft auger system rotates in opposite directions. A vacuum system, including a vacuum pump, which is connected to the vacuum drying chamber via pipelines and automatic valves; The microwave heating module has a horizontal cylindrical body with evenly distributed feed inlets, and the microwave heating module is connected to the vacuum drying chamber through the feed inlets; The PLC control system is electrically connected to at least the dual-axis auger system, the vacuum pump, and the microwave heating module, and is used to regulate the vacuum level, temperature, and stirring speed.

2. The vacuum microwave low-temperature drying equipment according to claim 1, characterized in that, It also includes a water vapor capture system, which includes a cryogenic refrigerator. The cryogenic refrigerator is connected to a condenser coil and a water trap via an input pipe. The water trap is connected to the horizontal cylinder via a pipeline.

3. The vacuum microwave low-temperature drying equipment according to claim 2, characterized in that, The PLC control system is electrically connected to the water and air capture system.

4. The vacuum microwave low-temperature drying equipment according to claim 1, characterized in that, The blades are spirally arranged on the rotating shaft. The blades include a shaft, one end of which is connected to the rotating shaft and the other end is connected to deflection blades. The deflection blades are angled relative to the horizontal plane of their respective phases.

5. The vacuum microwave low-temperature drying equipment according to claim 4, characterized in that, The deflecting blades are respectively configured as one or more rotating blade array groups along the circumference of the rotation axis. Each rotating blade array group includes at least two main deflecting blade groups. The main deflecting blade groups include at least one pair of deflecting blades tilted in opposite directions. A phase angle is set between the deflecting blades tilted in opposite directions.

6. The vacuum microwave low-temperature drying equipment according to claim 1, characterized in that, The vacuum system includes an automatic material suction structure connected to the horizontal cylinder, the automatic material suction structure comprising: The vacuum feed line is connected to the horizontal cylinder via the automatic valve; The PLC control module is configured to control the start and stop of the vacuum pump and the opening and closing of the automatic valve in stages to achieve vacuum gradient adjustment. A material filling sensor is installed on the side wall of the horizontal cylinder, and the material filling sensor is installed at 1 / 2 to 2 / 3 of the internal volume of the horizontal cylinder.

7. The vacuum microwave low-temperature drying equipment according to claim 1, characterized in that, The horizontal cylindrical body is connected to a sealed discharge structure, which includes: A sealed unloading device is connected to the bottom of the horizontal cylinder via a tapered tube; The electromagnetic shielded sealing door uses a reducer to drive a lead screw to achieve linear extension and retraction. The surface of the electromagnetic shielded sealing door is covered with lip-shaped silicone seals and an electromagnetic shielding mesh.

8. The vacuum microwave low-temperature drying equipment according to claim 7, characterized in that, The electromagnetic shielding sealing door has a telescopic stroke of 50-100mm, a sealing pressure ≥0.1MPa, an electromagnetic shielding mesh aperture ≤1mm, and an electromagnetic wave attenuation rate ≥99%.

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