DEHYDRATION OF SUGAR-BEET PULP IN SUPERHEATED STEAM AND HOT AIR

Abstract

The drying characteristics of sugar-beet pulp in superheated steam and hot air at three temperatures (130,157, and 183C) and three velocities (0.24, 0.32, and 0.37 m/s) of drying media (air or steam) under atmosphericpressure were studied. The drying rate was higher and the drying time was shorter in superheated steam than in hot air ofthe same temperature. The drying rate increased and the drying time decreased with increased temperature for bothsuperheated-steam drying and hot-air drying; however, the effect of temperature on superheated-steam drying wasgreater than on hot-air drying. At 157C, increasing the velocity of the drying medium did not affect the dryingcharacteristics of the samples dehydrated with hot air, but increased the drying rate at moisture contents greater than0.5 kg/kg dry basis (d.b.) for superheated-steam drying. Sugar-beet pulp dehydrated with either superheated steam or hotair under the same drying conditions (157C and 0.32 m/s) had the same water activities.