Drying of Wet Antibiotic Crystals in a Vacuum-Shelf Dryer Small-scale drying tests were performed in a vacuum-shelf dryer with wet antibiotic crystals contained in a tray at a solids depth of 2 cm. Water at 70°C was circulating through the shelves, and the absolute pressure was maintained at 100 mm Hg. The wet crystals initially had a water content of 70%. The solids reached dryness after 10 h of drying. It is proposed to dry these crystals in a large-scale dryer at a bed depth of 2.5 cm and using water circulating through the shelves at 70°C. The plant dryer can be operated at an absolute pressure no lower than 150 mm Hg. Estimate how long it will take to reach dryness in the large dryer. For changes in what variable is the estimated drying time the most sensitive?
