Flüssigphase-Rückvermischung in gepackten Blasensäulen

Liquid phase backmixing in packed bubble columns . Correlations for the axial liquid phase dispersion coefficient in bubble columns packed with metal Raschig rings and Pall rings are given as Pe_g = f (Ga, Re_g, H/D). The dependencies on physical and operational properties are discussed in detail with the aid of diagrams. Pall rings are not able to completely suppress greater turbulences and backmixing in columns of diameters D > 20 cm. A rule of thumb is also given for the apparent dispersion coefficient in this range. Raschig rings, however, are well suited for suppressing backmixing. The problems of adequate fulfilling of the model and undisturbed measurement of the backmixing behaviour are dealt with in detail.     

Verhalten von Blasen in Blasensäulen mit Bodenschwinger

Bubble columns equipped with an vibration exciter, which pulsates with a frequency between 40 and 400 Hz, show significantly improved mass transfer rates. This results from a reduction of bubble size by cleavage, the associated increase in surface area and, additionally, an intensive movement at the bubble interface. The observed phenomena are explained based on flow simulations. The energy required for a oscillating bubble column is less than for a gassed stirred tank.