GAS HOLDUP IN A BUBBLE-COLUMN WITH A SINGLE HOLE ORIFICE

An experimental study was performed on gas holdup, phi, measured by varing gas flow rate, hole diameter and unaerated liquid height in a bubble column with a single hole orifice as a gas distributor. For single orifices, two different flow regions existed in the column: the spouting and calming sections. The former section was the lower region in the column and the flow heterogeneity for bubble dispersion existed there over the whole range of gas flow rates in this study. The latter was the upper region representing the common bubble flow regimes. Though the border between two sections was nearly two times the column diameter. The value of phi in the spouting section was negligible, compared with that in the calming section. Since the bubble rising velocity in the calming section was constant and independent of the operating conditions at low gas flow rate, this flow region was considered as the free rising one. Gas holdup in this section was correlated by a dimensionless equation with the flow parameter defined by the ratio of the reference velocity in the free to that in the circulated rising regions, respectively.