Separation of Gas–Liquid Two-Phase Flow Through Independent Component Analysis

Two-phase flow measurement has attracted a major interest in the past four decades due to its wide range of applications in industry. This paper introduces a new method to separate the gas phase from the liquid phase through a blind source separation algorithm, without a separate device, based on the assumption that the two phases are separated and their independence is reflected in the statistical relation between the electrical signals generated by the process. Experimental data are obtained from a gas-liquid two-phase flow rig through electrical resistance tomography (ERT). An independent component analysis (ICA) method is applied to separate the gas phase from the liquid phase. The efficiency of the ICA method with the ERT data is assessed through experiments. The independent components (ICs) are interpreted by comparing them with the reconstructed images by ERT. The comparative studies show that ICA is effective in extracting phase information of gas-liquid two-phase flow, particularly for stratified, slug, and wave flows. Based on the extracted ICs, the cross-correlation technique is adopted to estimate the mean velocity of the liquid phase in the central area, the gas phase at the interface, and the liquid phase around the pipe wall and the liquid slug. Through correlating ICs representing different spatially independent processes from the upstream and downstream planes after the elimination of cyclostationary characteristics of ICs, the mean velocity of different spatially processes is obtained.