The Study on Image Data Acquisition System for Electrical Capacitance Tomography System

The subject investigated in this paper is oil-water two-phase flow, an image data acquisition system for 12 electrodes electrical capacitance tomography (ECT) of oil/water two-phase flow is discussed. This paper introduces a novel integrated structure of the ECT system for a capacitance sensor, in which the capacitance-to-voltage conversion circuitry for each electrode directly onto the electrodes such that the leads and its stray capacitance are eliminated nearly. The principle and design of a new AC-based micro-capacitance measurement circuit (MCMC) of controllable exciting sine-wave signal amplitude is presented and implemented as well as in this paper. The immunity to stray capacitances of MCMC is discussed and analyzed. The results of experiment results show that the non-linear error is 0.248%, the repeatability error is 0.281%, static error is less than 0.3% for capacitance measurement, and drift is 0.05% per hour. The circuit not only overcomes the limitations of existing circuit but also satisfies the requirement of ECT system in linearity, resolution and stability by the analysis of test data. The reconstructed section image, which is on the basis of image data captured, is in accordance with the facts.