Experimental study on hydrodynamic characteristics of gas–solid pulsed fluidized bed

The purpose of this study is to investigate the hydrodynamic characteristics of pulsed fluidized bed experimentally. Three different particles, silica with 196 μm mean diameter, alumina with 95 μm mean diameter and alumina with 10 μm mean diameter were introduced into the fluidized bed. Experiments were performed in 0.11 m ID and 0.5 m height fluidized bed. Pulsed airflow was introduced using square waves at 1 to 10 Hz pulsation frequency, which were generated using a solenoid valve connected to an electronic circuit. A high speed camera recorded the bed behavior to measure the bubble size and velocity. Results indicate that for alumina 95 μm the bed surface oscillation increases with decrease of pulsation frequency. Increasing the pulsation frequency decreases the bed expansion ratio and the bubbleʹs diameter and velocity. In addition, the mean bed pressure drop becomes closer to the continuous airflow by increasing the pulsation frequency. This study indicates that the pulsating airflow decreases the minimum fluidization velocity and enhances fluidization of fine cohesive particles.