Turbulent fluidization

In the flow regime of turbulent fluidization, pockets of gas (bubbles or sl ugs) no longer appear distinct. Clusters and strands of fine particles as w ell as voids of elongated and distorted shapes move rapidly in a zigzag man ner through the bed. The solids hold-up is quite high (25-35 % by volume) a nd at the indistinct bed surface, aggregates of particles are continuously ejected into the freeboard. Turbulent fluidization is often employed in ind ustrial fluidized-bed reactors because of efficient gas-solid contact, rapi d heat and mass transfer and limited axial mixing of gas. Although it accou nts for most commercial applications of gas-solid fluidization, the turbule nt fluidization has received far less attention than the adjacent flow regi mes of bubbling (or slugging) and fast fluidization. A number of empirical correlations are presented for prediction of the range of turbulent fluidiz ation. Turbulent beds exhibit non-uniform distributions of voidage/solids h oldup in both axial and radial directions. Some reactor models treat the tu rbulent bed as a single-phase homogeneous system, others assume the existen ce of two phases. Such aspects as energy dissipation, turbulence and chaos need to be explored to improve the knowledge of this turbulent fluidization regime.