Bed Expansion Characteristics of Liquid-Solid Fluidized Bed with Internals

E Ramaswamy,C Srinivasakannan,N Balasubramaniam

doi:10.5539/mas.v2n2p84

Abstract

It is attempted in the present investigation to study the influence of internals in the riser of liquid-solid fluidized bed. Experiments on bed expansion characteristics in liquid-solid fluidized bed have been carried out in a conventional liquid-solid fluidized bed and in a fluidized bed having string plates of spheres and twisted tapes as internals covering wide range in operating conditions. It has been observed in the present investigation that an increase in particle diameter, density and twist ratio is found to decrease the bed voidage and an increase in the pitch of the string increases the bed voidage. Further it has been observed that the bed voidage is higher in fluidized bed without internals when compared to fluidized bed with internals for a given operating conditions. A model based on slip velocity has been developed for predicting bed voidage and observed that more than 92% of the experimental data match with the model predictions within 10% error.

Highlights

Fluidized beds find extensive applications in chemical process industries as they provide large interfacial area, high degree of mixing, and temperature uniformity
A model based on slip velocity has been developed for predicting bed voidage and observed that more than 92% of the experimental data match with the model predictions within 10% error
Liquid-solid fluidized beds are increasingly used in chemical processes such as fermentation, biological wastewater treatment, flue gas desulfurization, ore reduction etc

Summary

Introduction

Fluidized beds find extensive applications in chemical process industries as they provide large interfacial area, high degree of mixing, and temperature uniformity. Fluidization can be achieved either by liquid or gas as fluidizing medium, gas fluidized beds have gained more importance in scientific community due to its far more applications. This is in spite of the fact that possible uses of liquid fluidisation in the mining industry were suggested as early as in 16th century as a means of separating solids of different sizes. The applications of liquid–solid fluidized beds are being extended for hydrometallurgy, food technology, biochemical processing, water treatment, etc A theoretical work is attempted to predict the bed expansion characteristics, based on slip velocity

Experimental

Slip Velocity

Findings

Conclusion