The investigation of bubble column and foam processes using electrical capacitance tomography

Foams are important in a variety of industrial processes including mineral production processes such as froth flotation. A variety of techniques have been used for their study such as microscopy, photography, casting-templating techniques, optical tomography and diffusing wave spectroscopy. In many process situations the delicate nature of foams necessitates non-intrusive measurement. In this paper detailed work is reported on applying electrical capacitance tomography (ECT) to low water fraction foams (<0.05). Potential applications are illustrated and discussed, including a demonstration of the ability to distinguish polyhedral foam and annular foam flow by analysis of pixelated images. The use of a method for the identification of flow regimes, which are dependent on surfactant concentration in a bubble column, is reported. (C) 2002 Elsevier Science Ltd. All rights reserved.