Measurement of gas hold-up profiles by gamma ray Tomography: effect of sparger design and height of dispersion in bubble columns

Radial variation of the gas hold-up was investigated in 0.385m i.d. bubble column using gamma ray tomography. Radial profiles were measured at three axial locations (HD/D= 0.259, 3 and 5). In all the experiments water was liquid phase and air was gas phase. Superficial gas velocity was varied from 0.06 to 0.3ms−1. Perforated plates were used as spargers. The free area of sparger plates (FA) and the hole diameter (d0) were varied in the range of 0.135 to 5.4% and 0.8 to 87mm respectively. The hold-up profiles were found to depend strongly on the sparger design, at least near the sparger. Further, the height of dispersion was found to influence the hold-up profiles near the sparger. All the results have been correlated on the basis of drift flux model and parabolic holdup profile