TWO-PHASE PRESSURE DROP IN A TRICKLE BED REACTOR INVOLVING NEWTONIAN/NON-NEWTONIAN LIQUID PHASE

Abstract

Pressure drop is an important parameter in the process design and performance of trickle bed reactors as it affects the energy requirements and hence the operating cost and sizing of the reactor. Various hydrodynamic factors that influence the two-phase pressure drop of a trickle bed reactor when Newtonian liquid phases are involved include gas flow rate, liquid flow rate, surface tension of the liquid phase, viscosity of the liquid phase, and bed characteristics such as porosity and sphericity of the packing material. For viscoinelastic fluid flow consistency index K and flow behavior index n are observed to affect the pressure drop significantly, whereas, for viscoelastic fluids, fluid elasticity leads to higher pressure drop. In the present study the effects of various parameters (involving bed characteristics and liquid-phase properties ranging from simple water-like Newtonian fluids to complex viscoelastic non-Newtonian fluids) on two-phase pressure drop are investigated. A wide range of correlations for two-phase pressure drop are available in the literature, however, none of the correlations seem to be applicable over a wide range of bed characteristics and fluid-phase properties as investigated in the present study. The experimental observations indicated that the pressure drop rises significantly when the flow regime changes from low to high interaction. Hence the data corresponding to low- and high-interaction regimes are treated separately to yield suitable correlations for Newtonian and non-Newtonian fluids. The correlations developed predicted the literature data for Newtonian liquid -phases to within±20%. The correlations are extended to predict two-phase pressure drop for viscoinelastic and viscoelastic liquid phases.