Separation

Drying

QUESTION 1 a It is intended to dry 8 kg of spherical wet catalyst pellets having a diameter of 12.7 mm in a through-circulation dryer. The pellets are in a bed of 63.5 mm thick on a screen. The solids are being dried by dry air entering at 82.2 C with a superficial velocity of 0.914 m/s and humidity of H= 0.01 kg-H2O/kg dry-air. The dry solid density is determined as 1522 kg/m, and the void fraction in the bed is 0.35. If the catalyst originally contains 40 percent moisture (wet basis) and the critical point is at 31 percent (wet basis), calculate the time it will take to dry the catalyst to 15 percent moisture content (wet basis)? (35 Marks)