Gas-liquid mass transfer has been investigated in gas-liquikolid three-phase stirred tank reactors with Newtonian and non-Newtonian liquids. Volumetric mass transfer coefficients and gas hold-ups were measured in a 0.2 m i.d. stirred tank reactor and the effects of low-density polymeric particles (p, =lo30 and 1200 kg/m3; up to 15 ~0 1 % ) on gas-liquid mass transfer were examined. The volumetric mass transfer coefficients in water were found to decrease due to the presence of solid particles at constant impeller speed and superficial gas velocity. On the other hand, solids loading led to higher mass transfer rates in non-Newtonian carboxymethyl cellulose aqueous solutions. Our previously proposed model for mass transfer in gas-liquid two-phase systems was extended to gasliquid-solid three-phase systems. Reasonable agreement was found between the predictions of the proposed model and the experimental data.
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On a etudie le transfert de matiere gaz-liquide dans des reacteurs a reservoirs agites gaz-liquide-solide triphasiques avec des liquides newtoniens et non newtoniens. Les coefficients volumetriques de transfert de matiere et les retentions de gaz ont ete mesurees dans un reacteur a reservoir agite de 0,2 de diametre interieur, et on a examine les effets de particules polymtkiques de faible densite (p, = 1030 et 1200 kg/m3; jusqu'a 15% en volume) sur le transfert de matiere gazliquide. On a trouve que les coefficients volumetriques de transfert de matiere dans I'eau diminuaient du fait de la presence de particules solides a vitesse de turbine et vitesse de gaz superficielle constantes. Par ailleurs, on a note que le chargement en solides menait a de plus grandes vitesses de transfert de matiere dans des solutions aqueuses non newtoniennes de carboxymethyl cellulose. Notre ancien modele propose pour le transfert de matiere dans des systemes gazliquide biphasiques a ete etendu h des systemes gaz-liquide-solides triphasiques. Un accord raisonnable a ete trouve entre les predictions du modele propose et les donnees experimentales.
Keywords: three-phase stirred tank reactor, mass transfer coefficient, gas hold-up, non-Newtonian liquid.