Experimental Evaluation And Modeling Of The Hydrodynamics In Structured Packing Operated With Viscous Waste Oils

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 degrees C, respectively) and a silicone oil (20 mPa s at 25 degrees C) in a laboratory-scale packed column (D-col = 0.12 m). The column was filled with structured packing made of corrugated sheets (Flexipac (R) 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 m(3) 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 m(3) 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. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.