TRANSITION TO TURBULENT FLUIDIZATION

摘要

The existence of turbulent fluidization has been in controversy, especially on its distinct characteristics and the criteria setting the boundary between bubbling and turbulent fluidization. It is shown in this paper that there exist unique characteristics of turbulent fluidization in the non-slugging system using fine Group A particles. As the gas velocity increases, the pressure fluctuation reaches a maximum value either due to the break down of large bubbles after a maximum size is reached or due to the reduction in the vertical separation distance between adjacent bubbles of maximum stable size. The reduction in the separation distance will eventually trigger the splitting of large bubbles when the trailing bubble moves into the turbulent wake region of leading bubbles. As a result, U_c can be used to demarcate the onset of turbulent fluidization quantitatively. A comparison between U_c data and transition velocity data obtained from visual observation confirmed that both criteria gave consistent results.