(61g) A Submerged Particle Model for Liquid Holdup in Packed Beds

New packing elements emerge all the time in the quest for improved gas-liquid-solid contact in packed towers while minimizing pressure drop.  Design of packed tower operations is still based on packing element specific empirical charts and it is still not possible to predict the transfer coefficients.  Liquid holdup is a key parameter that influences wetting efficiency, pressure drop and transfer rates. A new model for liquid holdup in packed beds is developed considering gas to flow around particles enveloped by a film of trickling liquid. Equation for gas phase pressure drop is developed by adopting Ergun’s equation incorporating the effect of presence of liquid phase on gas phase voidage and tortuosity for gas flow. The model equations are compared with the literature experimental data to evaluate the effect of parameters such as gas and liquid velocities, liquid properties, particle shape and size on liquid holdup and two phase pressure drop. The model equations compare reasonably well with experimental observations.