Flow Pattern Characteristics in Vertical Dense-Phase Pneumatic Conveying of Pulverized Coal Using Electrical Capacitance Tomography

Research on flow patterns can provide a better understanding of particle dynamics in dense-phase pneumatic conveying of pulverized coal. In this paper, electrical capacitance tomography (ECT) has been employed to study flow patterns in the 20 mm diameter vertical riser. Three flow patterns were identified on the basis of ECT image analysis, and their characteristics and formation mechanisms were discussed. The flow patterns at high solid concentration were more asymmetrical than those at low solid concentration. Solid concentration signals obtained from ECT were analyzed by different signal analysis methods including relative standard deviation (RSD), probability density function (PDF), and power spectral density function (PSD), which were verified to be effective enough to identify the characteristics of the different flow patterns. Additionally, the Bi model (Bi, H. T.; Grace, J. R. Int. J. Multiphase Flow1995, 21, 1229–1239) was modified to effectively predict chocking velocity in the vertical dense-ph...

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