MASS-TRANSFER AND DISPERSED PHASE MIXING IN LIQUID LIQUID-SYSTEMS .2.

The objective of this study is to develop and evaluate a new Monte-Carlo simulation algorithm to predict the effects of simultaneous drop breakage and coalescence on the hydrodynamics and mass transfer efficiency of two-phase liquid-liquid continuous flow stirred tanks at steady state. Statistical independence of the three drop-state variables (volume, age and solute concentration) has not been assumed, the dispersion being characterized by their three bivariate distributions (volume-concentration, volume-age and age-concentration). This represented a significant saving in core memory, while achieving a much closer description of the dispersion than previously to the real full trivariate behaviour. The algorithm, as implemented on the same CDC CYBER 170/720 digital computer used for our previous population balance work, performed only 15 times slower than its population balance alternative, but enabled relaxation of the previous assumption of statistical independence of the drop properties, which is often not valid in real systems. The algorithm has now been implemented on a simple 80286-based microcomputer, fitted with a mathematical co-processor, where it takes only about four times as long to run as on the CDC CYBER. The results predicted by this algorithm for the hydrodynamic and mass transfer behaviour (rigid and oscillating drop mechanisms) of liquid-liquid dispersions were subject to adequate satistical tests (χ2 and means stability), which validated the numerical sampling techniques used in the simulation and ensured that the final steady-state dispersed and continuous phase properties had been obtained. © 1990.