Electrical resistance tomography (ERT) for flow and velocity profile measurement of a single phase liquid in a horizontal pipe

Abstract

Electrical resistance tomography (ERT) is a novel, simple, and robust method of process imaging which uses non-invasive sensors located on the periphery of vessels to reconstruct a cross-sectional image of the vessel interior. This method of imaging when conducted on two adjacent planes on a pipe provides the ability to extract flow information. Previous studies have investigated this application on multi-phase flows in which the secondary phase provided the required pulse conductivity variation. In these studies the velocity profile and flow regime were identified using the common cross-correlation technique.This study investigates the novel application of ERT to single phase flow and velocity profile measurement. For this purpose a new measurement technique is also developed which excludes the limitation of “pulse” conductivity change in the cross-correlation technique. This new technique has been applied to saline flow and velocity profile measurement using a “step” change in the flow conductivity. The effect of flow speed, ERT measurement frequency, secondary solution conductivity and addition volume has also been investigated and the optimum settings selected. The optimum settings for this experimental setup resulted in an average accuracy of 97.0% for a secondary solution with conductivity more than twice the primary solution conductivity and 94.8% for a secondary solution with conductivity ∼67% more than the primary solution conductivity. This application and accuracy level has been further confirmed through 13%, 24% and 47% total solids content whole and skim milk experiments which resulted in an average accuracy of over 98%.