Gas hold-up profiles in foaming liquids in bubble columns

Abstract

Radial variation of gas hold-up was investigated in 0.385 m i.d. bubble column using gamma ray tomography. The gas phase was air and the liquid phase comprised of aqueous solutions of n-butanol at different concentrations (0-0.5% v/v). These solutions exhibit foaming behaviour at higher concentrations. Radial profiles were measured at three axial locations (H_D/D=0.259, 3 and 5). The fractional gas hold-up was compared with the air-water system under otherwise identical conditions. Superficial gas velocity was varied from 0.06 to 0.3 m/s. Two perforated sparger plates were used having the same free area (F.A.=0.42%) and two hole diameters (1 mm (multipoint sparger), and 25 mm (single point sparger)). The hold-up profiles were found to depend strongly on the sparger design and the concentration of the alcohol. All the results have been correlated on the basis of drift flux model.