Mass Transfer in Multiphase Mechanically Agitated Systems

Mass Transfer in Multiphase Mechanically Agitated Systems 95 for some time.When aeration was stopped and the bubbles escaped from the liquid, the steady state concentration of dissolved oxygen was measured.Apart from experimental studies, new methods are recently used to prediction the values of the volumetric mass transfer coefficient.Lemoine & Morsi (2005) applied artificial neural network to analyze mass transfer process in a gas-liquid system.Using CFD technique, Moilanen et al. (2008) modeled mass transfer in an aerated vessel of working volume 0.2 m 3 which was equipped with Rushton, Phasejet or Combijet impeller. Survey of the results for gas-solid-liquid systemThe critical impeller speed for the solid suspension in liquid can be defined as the impeller speed at which no particles resting on the bottom of the vessel longer then 1-3s (Zwietering, 1958).In multiple -impeller system introduction of gas into solid -liquid system implicate an increase in the impeller speed required for particles suspension just like in a singleimpeller system.For solid suspension multiple impeller systems would prove to be disadvantageous if the distance between impellers is greater than the diameter of the impeller as there is an increase in the critical impeller speed for solid suspension (Gogate et al., 2000).The data on the multiple -impeller systems working in the three -phase gas -solid -liquid systems are limited (Kiełbus-Rąpała & Karcz, 2009).Various aspects of the three -phase system stirring in the vessel equipped with more than one impeller on the common shaft were the aim of the studies in papers (