SINKING OF LARGE SOLIDS IN A FLUIDIZED-BED OF FINE PARTICLES AND THEIR SELECTIVE DISCHARGE FROM IT

A process was proposed to for direct reduction of fine iron are which is pelletized with heavy oil. To determine the practicality of the above process, two problems related to the fluidized-bed reactor were studied. (1) Experiments were performed to determine the residence time of a large particle in the fluidized bed by using a cold model. Conditions for realizing the long residence time of a large particle or piston flow-like residence time were found. Also, an empirical equation for the mean sinking velocity of a large solid was obtained. (2) A new methed of removing large particles from the fluidized bed was studied. A screw discharger whose blades have a number of holes was connected to the bottom of the fluidized bed. Consequently, discharge of the large particles without accompanying fine particles could be attained. © By THE SOCIETY OF CHEMICAL ENGINEERS, JAPAN.