Abstract4rithl solids hold-up data for three-phase batch-fluidized bubblebed and foam-bed systems are presented, using air as the gas phase, pure liquids and solutions as the liquid phase and quartz, coal and different catalyst powders as the solid phase. Effects of gas velocity, gas distribution, solid particle size, liquid surface tension, liquid viscosity and solid-liquid wettability parameter anz established. A correlation in terms of dimensionless groups containing these parameters is proposed.
A possible indirect way of evaluating the solid-liquid contact angles for powders from the proposed critical solids hold-up correlation is indicated.
CRITICAL SOLIDS HOLD-UP
THE maximum quantity of solids that can be held in suspension in a liquid medium agitated by bubbles or by mechanical stirrers in a detied system is termed critical solids hold-up. The knowledge of this is an important prerequisite for the physical design of three-phase batch catalysed bubble-red and stirred-tank reactors. While a number of investigations have been carried out relating the suspension of solid particles in stirreragitated vessels [l-12], information regarding suspension of solids with bubble agitation only appears to be relatively meagre.
PRESENT WORK
Critical solids hold-up data have been taken for three-phase gas-liquid-solid batch fluidized systems, using air as the gas phase, pure liquids and solutions as the liquid phase and quartz, coal and different catalyst powders as the solid phase. A generalized correlation for the critical solids holdup, based on these data and derived by means of dimensional analysis is presented.