Performance and Requirements of Process ERT Instruments

D. R. Stephenson1, T. A. York2, R. Mann1

1. School of Chemical Engineering and Analytical Science, University of Manchester, M60 1QD, UK.

2. School of Electrical and Electronic Engineering, University of Manchester, M60 1QD, UK Email: t.york@manchester.ac.uk

ABSTRACT

It has been 15 years since the development of the first dedicated Electrical Resistance Tomography (ERT) instrument for Process Tomography. During the mid-1990’s the University of Manchester Institute of Science and Technology (UMIST) Mk1b ERT instrument was commercialised and has been marketed as the Industrial Tomography Systems (ITS) P2000 since the late 1990’s. However, since the development of the UMIST Mk1b, specific ERT instrument design for Process Tomography has received relatively little attention. Recent exceptions include the bi-polar pulse instrument from the University of Cape Town, the LCT instrument from the University of Manchester / Syngenta and the High Speed Impedance Camera from the University of Leeds. Historically, practitioners of ERT have had two options, namely the development of in-house ERT instruments or the purchasing of a commercially available instrument. Hence, few comparative studies of instrument performance have been published. With the increasing capability, flexibility and confidence in 3-dimensional reconstruction methods, it appears timely to re-evaluate ERT instrumentation requirements from a process perspective. This paper aims to present a performance comparison of three readily available ERT instruments and to outline future requirements of process ERT systems. Metrics analysed include frame rate, strategy flexibility, signal-to-noise ratio, conductivity operating range and performance characteristics specific to mixing applications. The link between instrumentation noise and reconstructed images is presented and is intended as a guide to image reconstruction expectations, given instrumentation performance.

Keywords ERT, Instrumentation, Performance Comparison.