Experimental evaluation and modeling of the hydrodynamics in structured packing operated with viscous waste oils.

• Hydrodynamics of two waste oils and PDMS in a structured packing was investigated. • Pressure drop in the loading zone was lower than 450 Pa m−1. • Loading and flooding velocities were relatively low, especially using the viscous lubricant. • Billet-Schultes correlations were efficient to predict the loading and flooding points and the pressure drop. • Scale-up calculations proved that transformer oil can be used in an industrial scale packed column. The purpose of this work was to study the hydrodynamic behavior of two viscous waste oils (a transformer oil and a lubricant characterized by viscosities of 19 mPa s and 79 mPa s at 25°C, respectively) and a silicone oil (20 mPa s at 25°C) in a laboratory-scale packed column (D col = 0.12 m). The column was filled with structured packing made of corrugated sheets (Flexipac® 500Z HC) and was operated at counter-current. Thus, the gas superficial velocities at the loading point were in the range from 0.40 to 0.65 m s−1 for liquid loads between 1 and 24 m3 m−2 h−1, and, at the flooding point from 0.56 to 1.07 m s−1 for liquid loads between 6 and 36 m3 m−2 h−1. Both loading and flooding points were particularly influenced by the solvent viscosity, leading to a narrow loading zone for the most viscous solvent (lubricant). The pressure drop values remained reasonable, lower than 450 Pa m−1 in the loading zone, even for the lubricant. Billet-Schultes correlations were used for the prediction of the loading and flooding velocities and of the pressure drop. The specific constants of the model were determined. These correlations enable accurate predictions of the loading and flooding points, with an average relative error around 7–8%, and of the pressure drop in the loading zone, with an average relative error of 15%. Simulations were performed with the Billet-Schultes correlations and showed that high liquid holdup and interfacial area would be obtained with these viscous solvents in the selected packing. Scale-up calculations proved that it would be possible to implement the transformer oil at industrial scale in a packed column filled with the studied structured packing. [ABSTRACT FROM AUTHOR]