摘要：Loop type bubble columns have good performance of liquid
circulation and mass transfer by airlift effect, where the liquid circulation
time is an important measurable characteristic parameter. This parameter is
affected by the column construction, the aspect ratio of the column, the
cross-sectional area ratio of down comer to riser (R), and the superficial
gas velocity in the riser (UGR). In this work, the mean gas holdup and the
liquid circulation time (TC) have been measured in four types of loop airlift
type bubble column: concentric tube internal loop airlift type, rectangular
internal loop airlift type, external loop airlift type, external loop airlift with
separator. Air and tap water were used as gas and liquid phase,
respectively. The results have demonstrated that the mean gas holdup in
riser increases in proportion to UGR, and that it in downcomer changes
according to the geometric parameters of each bubble column. TC has been
found to conform to an empirical equation which depends on UGR and the
length of draft tube or division plate in the region of 0.33 < R < 1.
