Electrical Resistance Tomography System And Two-Phase Flow Measurement

Two-phase flow is one of the most common fluids in the nature, which also plays very important part in industry and daily life. Because of its complexity and variability, the real-time parameter measurement of two-phase flow becomes a difficult issue in the field of engineering and science.Many methods have been applied on measuring two-phase flow, the one with great perspective is Electrical Resistance Tomography (ERT) which can obtain the flow characteristic of two-phase flow by measuring the change of the conductivity in the sensing field that established by injecting exciting current into measured cross-section. The characteristic of this technique is non-intrusive, non-radiant, visualization and etc.The main achievements made in this thesis are as follows:1. The serial data-acquisition ERT system is designed with interface card and A/D transition card. Basing on the analysis of real-time performance of ERT system, the scheme of parallel data-acquisition system has been proposed. This new system uses digital I/O card and high speed A/D transition card to decrease the switch time of measured signal and to improve system performance.2. Combining the flow characteristic of gas/liquid two-phase flow in horizontal pipe with the operating principle of ERT system, the feature time of gas phase passing through each position of the measured cross-section is drawn from the time series of feature value of the measured boundary voltage from each sensing electrode. Along with the distribution of gas phase in pipe, these two parameters can be used for feature extraction and recognition of flow regime.3. The dual-plane ERT system has been adopted for the vertical two-phase flow real-time experiments on oil/gas/water three-phase flow facility. Many groups of experiments have been made with different separation of two sensing planes. The cross-correlation velocity is detained by correlating the feature value of measured data, and associating with drift-flux model and kinematic theory, the relation between the cross-correlation velocity and the kinematic propagation is investigated.