Effect of plate geometry on characteristics of fluid flow and mass transfer in external-loop airlift bubble column

The influence of plate geometry (single hole plate and perforated plate) on the characteristics of fluid flow and mass transfer in an external-loop airlift bubble column was experimentally examined using an air-water system. The gas holdup can be well correlated with the drift flux correlation including liquid circulation velocity expressed by the correlation obtained by Okada et al, (1996) irrespective of plate geometry. The bubble size distribution may follow a log-normal probability distribution. The Sauter mean bubble diameter affecting the gas-liquid interfacial area decreases with increasing gas velocity for a single hole plate, whereas it increases for perforated plate. Therefore correlation equations for Sauter mean bubble diameter are proposed for both a single hole plate and a perforated plate following the result by Okada et al, (1996). The specific gas-liquid interfacial area is also correlated for a single hole plate on the basis of the result by Miyahara et al, (1997) whereas the correlation is modified for a perforated plate with respect to an effect of hole diameter of perforated plate. In addition, it is found that the correlation for the liquid-phase volumetric mass transfer coefficient is expressed by the result proposed by Okada et al. (1996) regardless of plate geometry.