International Society for Industrial Process Tomography

Comparison of 2D and 3D Sampling in
Electrical Capacitance Tomography

J. Kryszyn, D. Wanta^*, T. Olszewski, W. T. Smolik

Division of Nuclear and Medical Electronics, Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland

^*Email: d.wanta@ire.pw.edu.pl

ABSTRACT

A sensor with several electrodes in one ring is used in typical industrial applications of electrical capacitance tomography. The three-dimensional information of the moving objects can be reconstructed from a time series of 2D slices or by direct application of a 3D sensor with multiple rings of electrodes. In this paper the comparison of 3D imaging of the moving objects for 2D and 3D data sampling is presented. A sensor with 8 electrodes in one ring and a sensor with 32 electrodes in 4 rings were used in the experiments. The numerical simulation and real measurements of a rigid body moving in the tomographic sensor were carried out. The object built from seven small PVC cylinders was used in the tests. The 3D numerical modelling was used to simulate both 2D and 3D measurements. The linear model was used to solve the forward problem. The permittivity distribution was reconstructed using a linear iterative algorithm. In case of 2D data sampling, the three-dimensional distribution of electric permittivity was reconstructed by interpolation from many temporal 2D slices. For the 2D and 3D sensors used in the experiments, it can be concluded that despite the low signal-to-noise ratio for measurements of inter-electrode capacitance values in the 3D sensor, the acquisition of data using a 3D sensor gives better imaging quality than using a 2D sensor. The significance of the obtained results for flow imaging is discussed.

Keywords small capacitance measurement, electrical capacitance tomography, dynamic process visualization, flow imaging

Industrial Application General