AXIAL MIXING IN A 15 CM DIAMETER RECIPROCATING PLATE BUBBLE-COLUMN

Axial dispersion coefficients (E) in the liquid phase have been measur ed by unsteady tracer response methods in a 15 cm internal diameter re ciprocating plate bubble column, using air and water in countercurrent and cocurrent flow. The operating variables studied were amplitude (0 .6-1.27 cm) and frequency (0-5 Hz) of reciprocation, and the superfici al velocities of the liquid and gas phases and the spacing between pla tes. Three types of plate were studied; conventional Karr-type plates with perforation diameters 1.43 cm, plates with smaller (0.635 cm) per forations, and single-perforation (doughnut) plates with internal diam eter 7 cm. Measured values of E ranged from about 1 cm(2)/s to a maxim um of 116 cm2/s. In general, the plates with 0.635 cm perforations gav e the smallest values of E while the largest values of E were obtained with the doughnut plates, due to vortex ring shedding. The single liq uid phase data for the three types of plate were approximately consist ent with the correlation of Stevens and Baird (1990). The gas-liquid f low results were interpreted in terms of several different hydrodynami c effects.