Seeing a new dimension - The past decade's developments on electrical impedance tomography

Multi-component and multiphase fluid flows exist in many industrial processes. The phase distribution and interfaces in an aqueous-based process or multiphase flow carries significant information about the processes. Due to the correlation of the multiphase and independency of each phase, the correct measuring of multiphase flow, in the terms of concentration, disperse interface, local velocity and mass flow rate, are of extremely challenged tasks. In 1990s, electrical capacitance tomography was originally developed for oil-water two-phase flow, then electrical resistance tomography was introduced from medical research to process engineering. Significant progress has been made during the past decade and now the technology has been proved as a powerful tool for mapping the concentration and velocity distributions of the second phase in two-phase flows, where electrical impedance differences between the two-phase fluids exist. Previous and current work on electrical resistance tomography by the author and his colleagues are reviewed. Developments on sensor, measurement, image reconstruction and application are also briefly introduced. At the end of the paper, existing challenges and prospect of new dimensions in process tomography are discussed.