Experimental research of flow patterns and pressure signals in horizontal dense phase pneumatic conveying of pulverized coal

Understanding flow patterns and their variability is important for optimal design and trouble free dense phase pneumatic conveying of pulverized coal in a horizontal tube. Employing the electrical capacitance tomography (ECT), six flow patterns were identified and utilized for quantitative analysis based on the value and distribution of cross-sectional solid concentration. The dense-phase flow patterns in the horizontal tube of the pneumatic conveying system were somehow variable even when the operating conditions were unchanged. The probability calculation results suggest changing multiple flow patterns with one or two dominant flow for each of the seven sets of experimental conveying conditions and that a finite change in the dominant flow pattern would occur with an increasing superficial gas velocity. The power spectral density (PSD) function and the Hurst exponent of the pressure signals of the pulverized coal were well correlated with its flow patterns in a horizontal tube. The PSD functions and probability density functions (PDFs) of the void fraction signals from ECT are found to be related with flow patterns and can be used to quantitatively identify flow regimes. The ECT data may therefore be utilized for monitoring the flow patterns in a horizontal tube employed for pneumatic conveying of pulverized coal.

Graphical AbstractThe sensor was composed of eight sensing electrodes and radial electrodes placed outside a PVC pipe with 20 mm ID and 1.5 mm pipe thickness. The eight sensing electrodes 80 mm long were supported by the radial electrodes.Figure optionsDownload as PowerPoint slideResearch Highlights
► Research flow patterns of pulverized coal dense phase conveying through ECT.
► Six flow patterns are classified and utilized for quantitative analysis.
► Correlate flow patterns and the measurement signals using various methods.