Solids flow pattern in continuous oscillatory baffled reactor

Abstract

Transition from batch to continuous processing is an attractive alternative for the production of pharmaceutical, fine and bio chemicals. In a number of such industrial reactions or separations, a solid phase is present either as a reactant, product or catalyst. Instead of conventional continuous reactors, the utilization of oscillatory flow reactors could be advantageous. The flow pattern of solids in a continuous oscillatory baffled reactor (COBR), into which solids are introduced continuously, was investigated experimentally and theoretically. The effects of operating conditions on a solids flow regime, solids mean residence time and dispersion and solids holdup were analyzed and quantified. Four solids flow regimes named as: Creeping solids flow, Dense solids flow, Dilute solids flow and Solids washout, were identified based on the ratio of the maximum oscillatory axial velocity to hindered settling velocity of particles, input power per volume for oscillatory flow and the concentration ratio between adjacent cells. The results demonstrate that increasing frequency and/or amplitude decreases the axial dispersion of solids, the ratio of solids to fluid mean residence time and the solids holdup. Inlet solids concentration has no significant influence on the axial dispersion but considerably affects the solids mean residence time and the solids holdup.