Detection of phase and other sharp boundaries using electrical capacitance tomography

P. J Clarka,b, A. N Tsoligkasa, M. J. H Simmonsb, S. Blackburnb, H. Stitta

a Johnson Matthey Technology Centre, Billingham, UK, TS23 1LB

b School of Chemical Engineering, University of Birmingham, Edgbaston, UK, B15 2TT

Abstract

The detection of a hard boundary using Electrical Capacitance Tomography (ECT) is difficult due to smoothing effects created by use of a reconstruction algorithm in creating a tomogram. Applying a thresholding technique to the tomogram re-creates the boundary and removes the transient region exhibited in 64-bit colour tomograms. In this work, the ability of ECT to detect different forms of interface and the sensitivity of image error to threshold gate value is explored. This is achieved by using a series of phantoms of different geometrical form and applying image analysis techniques to determine summed pixel error, phase area error and a characteristic length error of the tomograms.

Keywords: Capacitance; Threshold; Phase; Boundaries