Dehydration of sugar-beet pulp in superheated steam and hot air

The drying characteristics of sugar-beet pulp in superheated steam and hot air at three temperatures (130, 157, and 183 degrees C) and three velocitie s (0.24, 0.32, and 0.37 m/s) of drying media (air or steam) under atmospher ic pressure were studied. The drying rate was higher and the drying time as shorter in superheated steam than in hot air of rite same temperature. The drying rate increased and the drying time decreased with increased tempera ture for both superheated-steam drying and hot-air drying; however; the eff ect of temperature on superheated-steam drying was greater than on hot-air drying. At 157 degrees C, increasing the velocity of the drying medium did not affect the drying characteristics of the samples dehydrated with hot ai r bur increased the drying rate at moisture contents greater than 0.5 kg/kg dry basis (d.b.) for superheated-steam drying. Sugar-beet pulp dehydrated with either superheated steam or hot air under the same drying conditions ( 157 degrees C and 0.32 m/s) had the same water activities.