The effect of rolling amplitude and period on particle distribution behavior in a rolling circulating fluidized bed

Abstract

The effect of rolling amplitude and rolling period on particle distribution behaviors in a rolling circulating fluidized bed (RCFB) has been quantitatively clarified by means of the electrical capacitance tomography (ECT) technique. A series of experiments with a cold mode RCFB were performed while the rolling amplitude and rolling period varied from Θ=2.5° to 10.0° and T=5.0 to 15.0s, respectively. Based on the particle distribution images captured by the ECT sensor, three main characteristics of particle distribution behavior, namely the average particle volume fraction, the particle distribution stability and the particle distribution uniformity, were quantitatively estimated. As results, the particle distribution behavior in the RCFB was dominated by the shear effect, which was derived from the inertial forces and gravity in the radial direction of the riser. The positive influence of rolling amplitude on the shear effect caused augmentation of the particle volume fraction; however, particle distribution became unstable and heterogeneous. Meanwhile, although the characteristic fluctuation frequency of particle volume fraction was dominated by the rolling period, little effect of the rolling period on the particle distribution behaviors was observed due to its minimal influence on the shear effect.