Effective interfacial area in agitated liquid–liquid continuous reactors

Abstract

A chemical method has been used to quantify the e ective interfacial area in a ba4ed continuous stirred liquid–liquid reactor. Two and four straight paddle impellers were used in the experimental runs, at 34◦C, with hold-up fractions of dispersed organic phase between 0.061 and 0.166 and stirring speed ranging from 360 to 1500 rpm. In:uence of the residence time on the formation of the interfacial area generated in this system was not registered; however, di erences were reported between continuous and batch mode operations. The interfacial area was correlated to hold-up fraction and Weber number by a new empirical model proposed in this work. This model allows to use only one equation to calculate the interfacial area in this continuous stirred reactor in the wide range of operating conditions tested (490¡We¡9600), which include di erent :ow regimes. This is a relevant contribution as previous studies in this =eld only contemplate turbulent :ow. In the transitional regime the mean drop size diameter decreases abruptly with Weber number, but this pattern changes in the higher range ofWeber where the dispersed drops become smaller very smoothly. This pattern does not depend on the agitator used or hold-up fraction. The mean drop size diameter is smaller for the four paddle impeller and increases with hold-up fraction. The model developed may be applicable to dispersions in aromatic nitration reactors, improving its operation and design.