Q6: A wet solid is dried from 28 per cent to 10 per cent moisture, under constant drying conditions in 20 sec. If the equilibrium moisture content is 5 per cent and the critical moisture content is 15 per cent, how long will it take to dry solid from 23 to 8 per cent moisture under the same conditions?

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3 A continuous countercurrent adiabatic rotary drier is being designed for the production of 500 lb/h of a product containing 2% moisture from wet crystal containing 30% moisture, wet basis. The air entering the drier will have a dry-bulb temperature of 230°F and a wet-bulb temperature of 102°F. The air leaving the drier will be at a temperature of 115°F. Because of the small size of the crystals, the highest allowable air velocity is 10 lb dry air/ft2-min of drier cross section. Find: a. Dry air required (lb/min) b. Cross-sectional area of the drier c. Length of drier required if the volumetric coefficient of heat transfer is 25 BTU/ft3-h-°F

Choose the correct option: Which of the following is not a unit operation? a) Crystallization b) Evaporation c) Cracking d) Distillation