RESIDENCE TIME DISTRIBUTION IN A WIPED LIQUID-FILM

The present work concerns the evaluation of experimental residence tim e distribution (RTD) curves obtained in a wiped liquid film formed on the surface of the evaporator cylinder of a molecular evaporator. The dependent variables in the study are the peripheral load and liquid vi scosity. The wiping process is modelled by a cascade of apparatuses wi th laminar falling film ideally mixed at the exit from each stage in a mixer having zero thickness. The comparison of experimental and model data shows that the model developed explains well the actual processe s taking place in the him wiped by a segmented wiper. By comparison of the shape of the experimental RTD curves with theoretical model curve s, a criterion can be derived, indicating the efficiency of wiping.