Bed collapse behavior of pulsed fluidized beds of nano-powder

An important class of assisted fluidization techniques, which are neither energy-intensive nor suffer from post-processing issues, is based on pulsation of inlet gas flow to the fluidized bed. Collapse experiments have been carried out in a pulsed-flow fluidized bed containing a widely used nano-powder that shows strong agglomeration behavior. Pulsation in the inlet air flow was introduced using 0.1 Hz frequency square wave that controlled opening and closing of a solenoid valve. Transients of the total pressure-drop across the bed were carefully recorded using fast-response pressure transducers connected to a data acquisition system. Flow transients were also monitored during the bed collapse. Average size of nanoparticle agglomerates was computed using a mathematical model reported in the literature. Flow pulsation was found to substantially reduce the average agglomerate size of the nano-powder.