Electrical Resistance Tomographic Measurment Based On The Phasor Voltage By Injecting Dual Current Sources

Electrical Resistance Tomography (ERT) is a kind of Process Tomography (PT) using resistivity measurement of the two-phase flow. Despite that many challenges remained in ERT technology development, the technology possesses some unique edges over other measurement techniques towards process measurement and has been gradually moving closer to industry applications.This thesis presents a preliminary research of using multiple phase-controlled current sources to enhance measurement sensitivity and in particular improve ERT image reconstruction quality. Detailed researches on a dual-current injecting based ERT instrumentation are presented. Both the forward solver and reconstruction methods of the dual-current ERT are given and the results are discussed according to the simulation.The main contributions and works are as follows:1. Extended the conventional voltage amplitude measurement of a ERT system to voltage phasor measurement. Tomographic images based on phasor measurement are obtained. This is a novel technical addition to the existing ERT instrumentation technology and potentially it presents a better chance of yielding a better image resolution over existing amplitude based ERT systems equipped with an identical electrode system setup.2. Several image reconstruction methods using voltage phasor measurements are attempted. Though the improvements on image reconstructions are so far limited it sets a foundation for further research.3. Introduced several dual-current source excitation modes, and obtain a large number of independent measurements by controlling the phase difference between the two current sources. Based on these measurements reconstructions using LBP, STM, MNR, neural network algorithms are given and their results are discussed respectively.4. As an attempt to improve image resolution, an independent investigation work of introducing a rotatable shaft electrode into the existing ERT electrode setup is given. This may prove useful for some applications where a shaft electrode might be installable in the center region of a process.