Research On Gas/Liquid Two-phase Flow Measurement In Horizontal Pipeline Based On Electrical Resistance Tomography

The two-phase flow system exists widely in industrial processes, such as power, chemical, petroleum and metallurgy industries. Research on hydrodynamics, mechanisms and accurate measurement of parameters of two-phase flow are very important for the development of modern industry. However, because of its complexity and variability, the real-time parameter measurement of two-phase flow becomes a difficult issue.As a kind of non-destructive and visible measurement techniques, electrical tomography (ET) has found important applications in multi-phase flow measurement area, due to its low cost, fast response and portability. This dissertation focuses on the application of ET technique, especially electrical resistance tomography (ERT) technique, in gas/liquid two-phase flow measurement in a horizontal pipeline.The main achievements are listed as follows:1. The soft sensing model of gas/liquid two-phase flow in horizontal pipe has been established to identify flow regimes based on ERT technique. The features from second-order statistics, higher-order statistics, time domain and time-frequency domain are extracted. Experimental results indicate that the method of multi-feature information fusion which combined the feature extraction methods could better express the essential information of gas/liquid two-phase flow, and achieve a higher identification rate of flow regimes.2. Having obtained data of a gas/liquid flow by ERT, Independent component analysis (ICA) method has been applied. Experimental results demonstrate extracted independent components, having explicit physical meaning, correspond to the gas phase and the liquid phase separately. Good agreement between the independent component with the maximal kurtosis and liquid slug fluctuation of slug flow was observed. The interface fluctuation can be obtained by applying the multi-resolution analysis to extracted independent components.3. Based on the extracted liquid slug fluctuation, combined with cross-correlation technique, the ERT system was applied to estimate characteristic parameter of slug flow in a horizontal pipeline. The mean velocity and the length of liquid slug were obtained. 4. Based on the extracted indepentdent components, the cross-correlation technique was adopted to estimate the mean velocity of the liquid phase in centre area, the gas phase at the interface and the liquid phase rounding pipe wall.