STATIC INSTABILITY ANALYSIS OF CIRCULATING FLUIDIZED-BEDS AND CONCEPTOF HIGH-DENSITY RISERS

An instability analysis has been carried out to elucidate the unsteady flow conditions encountered in the typical circulating fluidized bed units in light of the conveyor-solids feeder interaction. The results successfully predict the critical velocity and the maximum solids circ ulation rates reported in the literature and explain the origin of suc h unstable conditions. Furthermore, the simulation, for the first time , reveals the importance of unit structure in improving the performanc e of circulating fluidized bed systems. Finally, the concept of a high -density circulating fluidized bed is proposed.