Rotating double-cone vacuum dryer

FIG. 12-75 Rotating (double-cone) vacuum dryer. (Stokes Vacuum, Inc.)... 

TABLE 12-28 Standard (Double-Cone) Rotating Vacuum Dryers ... 

Performance and Cost Data for Batch Vacuum Rotary Dryers Typical performance data for horizontal pan vacuum dryers are given in Table 12-27. Size and cost data for rotary agitator units are given in Table 12-28. Data for double-cone rotating units are in Table 12-29. 

Tumbler Vacuum Dryer. This dryer is designed for drying of chemical, pharmaceutical products which are not sticky. Its double cone rotating shape ensures direct contact between the material and the heated surface, resulting in uniform heat transfer. 

For the first group the following types of dryers are generally used convective (tray, band, fluid bed, flash dryers, and their modifications) or contact (vacuum dryers such as double-cone dryer-blender, conical dryer with rotating helical mixer, paddle dryer). Pastelike materials are dried in tray dryers, band dryers equipped with extruding devices, and spin-flash dryers. Finally, thin pastes can be dried in spray dryers or on fluid beds or spouted beds of inert particles. Small amounts of solutions and suspensions are generally freeze-dried, especially if the product is thermolabile. 

In a double cone dryer ( mixing dryer ) a drying drum with the form of a double cone revolves around an axis of rotation, which is perpendicular to the drum axis. Bulk material with a poorer flow behavior is dried in batches, usually under vacuum conditions. 

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