Measuring Material Distributions of Multiphase Flows in Electrically Conducting Vessels Using Electrical-Impedance Tomography

Abstract

An implementation of resistive electrical-impedance tomography (EIT) for measuring material distributions of multiphase flows in vessels with electrically conducting walls is presented. Seven ring electrodes are equally spaced on a thin nonconducting rod that is inserted into the vessel. The vessel wall is grounded and serves as the ground electrode. Voltage distribution measurements are used to numerically reconstruct the time-averaged impedance distribution within the vessel, from which the material distributions are inferred. Experimental results for the case in which the rod is inserted coaxially into a liquid-filled vertical standpipe containing beds of different heights of nonconducting solid particles are presented. Agreement between the direct measurement and the numerical reconstruction of the particle-bed height is good. Application of this technique to a pilot-scale slurry bubble-column reactor is discussed.

Electrical-Impedance Tomography for Opaque Multiphase Flows in Metallic (Electrically-Conducting) Vessels

“…A study verifying the feasibility of using the wall of an electrically conducting vessel as ground was completed (Liter et al 2002). The results of this study are summarized here.…”

“…An existing EIT system designed for use in nonconductive vessels (George et al 2000c) was modified for this study so that it could be employed in metallic vessels. This modified system was first used in a proof-of-concept experiment to measure the height of a packed bed of nonconducting solid particles submerged inside a liquid-filled steel standpipe (Liter et al 2002). Once the system proved effective in making quantitative phasevolume fraction measurements of a stationary liquid-solid mixture in metallic vessels, it was deployed in the SBCR facility to make phase-volume fraction measurements of gas-liquid flows at various flow conditions.…”