Oxygen transfer characteristics in a pilot scale surface aeration vessel with Simcar aerator

The volumetric mass transfer coefficient, K(L)a, was determined by dynamic method in a surface aerated pilot scale squared vessel up to 0.531m(3) equi pped with Simcar type impeller. Through surface aeration, the oxygen transf er characteristics were investigated with the variations of operating varia bles such as stirring speed, impeller diameter, liquid height and power inp ut per liquid volume (Po/V). It was seen ham the results of different oxyge n concentration absorption that the dynamic method might lead to errors in K(L)a when air was used for absorption. To provide reliable K(L)a values me asured by dynamic. the K(L)a data using pure oxygen were used and confirmed with feeding steady-state method (FSM). As expected, K(L)a depends on Po/V , impeller size and liquid height. However, for Simcar type impeller, the K (L)a shows linear dependency on Po/V in contrast to majority of correlation s reported in the literature which shows K(L)a a (po/V)(0.65) for disk type impeller. Moreover, it was interesting to find that the bubble behaviors i nside the vessel computed by computational fluid dynamics (CFD) could expla in qualitatively the K(L)a changes with operating variables. For the purpos e of scale-up procedures, the empirical correlations for predicting K(L)a w ere developed within +/-2% accuracy.