An Online Real-time Velocity Profiling System using Electrical Resistance Tomography

T. M. Long1, A. J. Wilkinson1, E. W. Randall2 and A. P. N. Sutherland3

1Department of Electrical Engineering at the University of Cape Town, South Africa

2Department of Chemical Engineering at the University of Cape Town, South Africa

3Flow Process Research Center at the Cape Peninsula University of Technology, South Africa E-mail: Timothy Long: mr.tim.long@gmail.com

ABSTRACT

A system to display velocity profiles of the flow of a slurry through a pipe online and in real-time has been developed. The system uses an electrical resistance tomography instrument developed by the University of Cape Town to generate resisitivity profiles through two cross sections of the flow which are cross correlated on a pixel wise basis to produce a velocity profile. The software developed employs a highly modular structure that allows different image reconstruction and cross correlation algorithms to be implemented and tested without substantial changes to the rest of the application. Using an 2.67GHz Intel Celeron processor with 500MB RAM, the system can calculate a velocity profile in significantly less time than taken to capture the data used in the calculation, indicating the system is capable of real-time performance. By overlapping correlation windows, a velocity profile frame update rate of one frame every two seconds can be achieved. Typical velocity flow profiles generated by the system are presented based on data captured using the Flow Process Research Center at the Cape Peninsula University of Technology's pipe flow test rig. Results for a sliding bed flow regime of a 5% kaolin, 10% sand slurry are shown.

Keywords ERT, cross-correlation, real-time, multi-phase flows