Drying Characteristics of Ragi using Circulating Fluidised Bed
Author Affiliations
- 1Dept. of Chemical Engineering, Kongu Polytechnic College, Perundurai 638 052, Tamilnadu, INDIA
- 2Dept. of Chemical Engineering, Kongu Engineering College, Perundurai 638 052, Tamilnadu, INDIA
Res.J.chem.sci., Volume 3, Issue (1), Pages 67-71, January,18 (2013)
Abstract
A Circulating Fluidized Bed is a type of gas-solid reactor consisting of a riser in which a gas-solid suspension is transported vertically upwards and separated at the top by gas-solid separators. After separation, the suspension is recycled to the bottom via a stand pipe or down comer. The behavior of CFB differs from a conventional fluidized bed, because of absence of bubbles and entrained flow of solids. A CFB operates at much higher gas velocities than those used in conventional fluidized bed and lower than those used in pneumatic conveying. Circulating fluidized bed is finding increased industrial applications in recent years. One such application is extension of a CFB for granular materials drying. It is essentially a process of simultaneous heat and mass transfer and a very common process in many of the chemical process industries. In this article an attempt was made to study the hydrodynamic properties of ragi in Circulating Fluidized Bed. Experiments were conducted in a column of 0.05m internal diameter and 1.6m long covering a wide range of operating conditions. The transport velocity was estimated by emptying time technique, the effect of pressure drop with axial co-ordinate for different gas mass flux and solids circulation rate, the effect of voidage and the effect of solid circulation rate with pressure gradient. In the present work an attempt has been made to dry in the riser of the circulating fluidized bed covering a wide range of operating parameters. The effects of various operating parameters such as initial moisture content on exposure time, moisture content with drying rate and relative moisture content with exposure time with varying temperature of heating medium. The results obtained are quite satisfactory with literatures.
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