Extraction of caprolactam with toluene in a pulsed disc and doughnut column - Part II Experimental evaluation of the hydraulic characteristics

In Part I of this study a theoretical model was recommended describing the hydraulic characteristics, being Sauter drop diameter, hold-up, operating regimes, and operational window, of caprolactam extraction in a pulsed disc and doughnut column. In order to confirm the theoretical model pilot plant experiments for the caprolactam forward and back-extraction were performed to determine the hydraulic characteristics as a function of the operating conditions. The experimental conditions covered the industrial operating range. All hydraulic experiments were performed at equilibrium conditions in order to avoid the influence of mass transfer. In the determination of the operational window flooding because of too low pulsation was qualitatively observed, while it was found that at high pulsation phase inversion was limiting for the back-extraction process and flooding for the forward extraction process. Application of the in Part I recommended theoretical model for the description of the obtained hydraulic data resulted in an accurate description after fitting the drop diameter, hold-up, and phase inversion data.