Passive acoustic bubble sizing in sparged systems

Passive acoustic bubble sizing was investigated in both controlled tests an d in a stirred, sparged tank typical of the biotechnology or minerals proce ssing industries. Acoustic techniques have promise for industrial systems w here other bubble analysis methods are impractical. Acoustic signals were s tudied for bubbles precisely formed at higher airflow rates. Acoustic pulse s varied with bubble production rate as well as with bubble size. A techniq ue of windowing pulses is proposed. Two alternative versions of this window ing technique were applied to a stirred, sparged tank, giving good agreemen t. It was shown that, in some cases, it may also be possible to acousticall y estimate the spatial distribution of void fraction.