INVESTIGATION OF THE GAS HOLD-UP OF OXYGEN AND HYDROGEN IN DIFFERENT AQUEOUS-ELECTROLYTE SOLUTION .1. EXPERIMENTAL INVESTIGATIONS

By measuring the static pressure drop in a glass bubble column, the ga s hold-up of oxygen and hygrogen in several electrolyte solutions was determined. A homogeneous bubble flow regime existed up to a gas throu gh-put of some 4 cm/s in the bubble column. It was found that the gas hold-up is mainly determined by the impediment to coalescence. The vel ocity of bubbles in different solutions was measured with an ultrasoni c doppler velocimeter. The velocity measurements indicated that coales cence already occurs at low gas through-put. A strong dependence of th e bubble velocity on the electrolyte concentration was observed. When the velocity of the bubbles drops, the concentrations are close to val ues confirmed by other authors to be the critical concentrations for c oalescence. By studying the hydrodynamics in the bubble column at a ga s through-put less than 4 cm/s a zone with circulation flow was detect ed above the gas sparger. Over this zone there was homogeneous bubble flow.