Intensification of mass transfer in the pulsed bubble column—Comparison of the efficiency of static and pulsed aerator

Abstract

Introduction of pulsations to the classical bubble columns makes it possible to reduce the size and velocity of flowing gas bubbles and to obtain nearly spherical shape. As a result, gas hold-up and interfacial area are increased which obviously has an effect on the intensification of mass transfer.In the work the values of gas hold-up and volumetric mass transfer coefficient obtained in the pulsed bubble columns with static and pulsed aerator were compared. In the tests two types of aerators were used: the first one was static, while the other one was a pulsed aerator fixed rigidly on the surface of the exciter disk. In both cases pulsations with the resonant frequencies up to 70 Hz and amplitude of 0.25–2 mm were introduced into the system, and the apparent gas velocity was set within 3.1–9.3 mm/s.Equations were proposed to calculate gas hold-up and volumetric mass transfer coefficient with accuracy of ±25% and ±30% for the aerator pulsating at resonance frequencies.Using a pulsed aerator in most cases lower gas hold-up was obtained than in the case of a static aerator. The volumetric mass transfer coefficient was higher when the static aerator was used.