POWER DISSIPATION AND HOLDUP IN A GASSED RECIPROCATING BAFFLE-PLATE COLUMN

The time-averaged power dissipation rates and gas holdups have been me asured in a 15 cm diameter glass column provided with reciprocating do ughnut baffle plates (internal diameter 7 and 9 cm). Most of the data were obtained at a reciprocation frequency of 5 Hz with amplitude in t he range 1 to 10 mm. The continuous phase was water and the dispersed phase was air, supplied at superficial velocities mainly in the range 0.32 to 1.14 mm s(-1). The power dissipation rates agreed with previou sly proposed models; the quasi-steady state model at high amplitudes a nd the acoustic model at low amplitudes. The pressure/displacement wav e forms for the plate stack were affected by dispersed gas. The gas ho ldup was increased strongly by reciprocation, with entrainment of gas bubbles into the vortices that formed at each plate. The doughnut plat es are more effective, for a given power input, than conventional plat es with multiple perforations reported in previous literature.