Reducing the Presence of Clusters in Bubble Size Measurements for Gas Dispersion Characterizations

Abstract

This short communication evaluates a new strategy to sample bubbles in gas dispersion characterizations. Bubble size is measured in a bidimensional flotation cell using the McGill bubble size analyzer under different types of frothers, frother concentrations and superficial gas rates. The original design of this bubble viewer is modified, changing the deflecting system to photograph only a fraction of the bubbles entering the device. As a result, the new design increases the ability to successfully identify bubbles by a maximum of 20% using an automated algorithm. This increase is caused by a reduction in the formation of clusters in the visual field. The improvement, which is a function of the operating conditions, is most significant in the transition from ellipsoidal/ellipsoidal–turbulent regimes (no frother or low frother concentrations) to conditions with an over-agglomeration of bubbles in the visual field (high superficial gas rates and high frother concentrations). A comparison of the bubble size parameters obtained from the original and proposed deflecting systems shows that the new design does not distort the estimated bubble size distributions. To complement the research findings, alternative sampling designs, using new or existing segmentation algorithms, are then proposed to improve gas dispersion characterizations at different scales.