Flow Regime Transition in a Trickle Bed Reactor

Abstract

ABSTRACT Hydrodynamic behavior of a trickle bed reactor is dependent on the flow regime that arises when gas and liquid flow concurrently downward in the reactor. Empirical or semi-analytical models available in the literature do not predict to satisfaction the transition between the trickle and pulse flow regimes in cocurrent down flow in a TBR. In the present study, flow transition between trickle flow (low-interaction) and pulse flow (high-interaction) regimes was experimentally observed for different non-foaming Newtonian and non-Newtonian liquid phases under concurrent down flow conditions with air in a packed bed using different bed configurations. The effect of bed geometry along with fluid phase properties has been considered to modify the flow map coordinates, so as to collapse the data corresponding to different bed configurations and Newtonian liquid-phase properties onto a single curve (within±20%). An empirical correlation for the prediction of Newtonian liquid-phase mass velocity at the transition between high interaction and low interaction regimes was developed, which assumes the form: The correlation was found to be in good agreement with the experimental data available in the literature for different Newtonian liquid-phase systems including data on nonspherical particles. This correlation is found to predict the transition satisfactorily when liquid-phase viscosity was replaced by apparent viscosity in the case of viscoinelastic liquid-phase systems. The correlation was further extended to predict the transition for a viscoelastic liquid-phase system with the introduction of the Weissenberg number as: