Counter-rotating Conical Vacuum Dryer's Vacuum Drying Technology

The Double-conical Rotating Vacuum Dryer is suitable for the vacuum drying and mixing of powdered and granular materials in industries such as pharmaceuticals, food, and chemicals. It is particularly applicable to materials with the following requirements: heat-sensitive materials that cannot tolerate high temperatures; materials that are easily oxidized and hazardous; materials that require solvent and toxic gas recovery; materials that require extremely low residual volatile content; materials with specific requirements for crystal shape; and materials that require thorough and uniform mixing.

The twin-conical rotary vacuum dryer employs a vacuum system to both evacuate and heat the material being dried simultaneously. This allows the moisture within the material to diffuse to the surface through pressure or concentration gradients. Water molecules (or other non-condensable gases) gain sufficient kinetic energy at the material surface, overcoming intermolecular attractive forces before diffusing into the low-pressure space of the vacuum chamber, where they are removed by the vacuum pump, thereby separating from the solid. Due to the small temperature gradient between the internal and external parts of the material during vacuum drying, and the osmotic effect, moisture can move and collect independently, effectively overcoming the dispersion phenomenon caused by hot air drying. The heat transfer coefficient U of the jacket of the twin-conical rotary vacuum dryer is independent of the operating pressure, with U ranging from 116 to 140 W/(m²·K) for non-agglomeration materials and from 80 to 93 W/(m²·K) for agglomerative materials. The heat transfer area is calculated based on the area of the material contacting the cylinder wall. The cylinder of the twin-conical rotary vacuum dryer is designed as a pressure vessel, with the inner cylinder subjected to external pressure and the outer cylinder to internal pressure.

The twin-conical rotary vacuum dryer extracts the material through the vacuum pump via the vacuum exhaust pipe. Due to the vacuum state inside the drum and the rotation of the drum, which causes continuous up-down and inside-out movement of the material, the drying speed is accelerated, efficiency is improved, and uniform drying is achieved. The twin-conical rotary vacuum dryer system mainly consists of the twin-conical rotary vacuum dryer, condenser, dust collector, vacuum suction system, heating system, cooling system, and electrical control system. The vacuum drying process involves placing the material to be dried in a sealed drum, using the vacuum system to create a vacuum while continuously heating the material. This causes the internal moisture of the material to diffuse to the surface through pressure or concentration differences. Water molecules (or other non-condensable gases) gain sufficient kinetic energy at the material surface, overcome intermolecular attractions, and diffuse into the low-pressure space of the vacuum chamber, where they are then removed by the vacuum pump, completing the separation from the solid.

Technical Requirements for the Bi-conical Rotating Vacuum Dryer

(1) Operation Method: The vessel is heated under vacuum conditions by introducing heat transfer oil or hot water into the jacket, with the heat transferred through the inner wall of the vessel to the wet material. After absorbing heat, the water vapor or other gases from the wet material are drawn away through the vacuum pump via the vacuum exhaust pipe.

(2) Internal tank design pressure: -0.1 to 0.5 MPa; jacketed heat transfer oil heating, jacket design pressure ≤ 0.3 MPa.

(3) 200L capacity drying chamber with enameled lining, withstands up to 130 degrees Celsius; inner and sandwich layer temperature display.

(4) Solvent recovery unit equipped, variable frequency speed control, explosion-proof motor.

Material Requirements: Inner Liner: Enamel; Jacket and Frame: Q235A; Outer Wall: SUS304 Stainless Steel.