Dry, hot air and superheated steam were used as the drying
gases. For the hot air treatment, dehumidified air was allowed to
flow into a heater (electric furnace) and then into the fluidized bed.
At the start of the experiment, the hot air was preheated by
pumping into the fluidized bed at atmospheric pressure, and the
bed temperature was controlled at the experimental temperature
(333 K). For the superheated steam treatment, a certain amount of
water was pumped into a heater (electric furnace) where the
temperature was 573 K; all of the water that was allowed to flow
into the heater was evaporated (the steam temperature was the
boiling point of water at the chamber pressure: 323 K at 12 kPa).
The evaporated water (steam) was allowed to flow into the bottom
of the fluidized bed. The steam was superheated to the drying
temperature (333 K) in the fluidized bed covered with a ribbon
heater.