Flow Characterization of Dense-Phase Pneumatic Conveying System of Pulverized Coal through Electrostatic Sensor Arrays

Experiments are performed in a dense-phase pneumatic conveying system of pulverized coal, and electrostatic signals and coal particle distribution images over cross-section of the pipeline at superficial gas velocities of 5.7 m/s, 6.9 m/s, and 8.1 m/s are obtained through use of electrostatic sensor arrays (ESA) and electrical capacitance tomography (ECT), respectively. In combination with ECT imaging results, the output signals of the ESA are analyzed by FFT and approximate entropy method. Results show that characteristic of particles motion and its change with increasing superficial gas velocity are different in the dense and dilute phase region of the pipe. With increasing the superficial gas velocity, the peak frequency of the electrostatic signal increases linearly in dense-phase region, while that in dilute phase region is nonlinear, implying that the increase of the axial particles velocity is the main dynamic change, while in dilute phase regions, the particles velocity fluctuation in the radial direction cannot be ignored. The ApEn value of the electrostatic signal in dense phase region is larger than that in dilute phase region. When the ApEn value difference of the electrostatic signals is smaller, the pulverized coal particles are better suspended