Application of a Twin-plane Electrical Capacitance Tomography Sensor for Characterising Bubble Behaviour in a Gas-solids Fluidized Bed

Fluidized beds have been used extensively in general chemical engineering applications. However, due to their complex hydrodynamic characteristics, conventional measurement techniques are insufficient to obtain a full understanding. Electrical Capacitance Tomography (ECT) has been developed as a non-invasive measurement technique and applied to study gas-solids fluidized beds. This paper describes experiments carried out in a bench-scale fluidized bed using air and silica sand as gas-solids system. A twin-plane ECT sensor with 10 mm long measuring electrodes was designed and fabricated to study the single bubbling regime. This was based on numerical simulations to ensure that the measured capacitance values are within the detectable range of the ECT system. 2D and 3D frame-based visual analysis of bubbles formed in single bubbling regime are presented. Averaged bubble rising velocity derived by cross-correlation technique has been compared with existing empirical correlations. Good overall agreement has been found.