Interrelation of Flooding and Complete Dispersion in Agitated Gas‐Liquid Contactors

Abstract

Despite the fact that the complete dispersion characteristics in agitated gas-liquid contactors are operationally important, the flooding-loading transition is widely used as a design criterion, due to its experimental convenience and accuracy. Moreover, limited data are available in the literature on the interrelation of the flooding-loading and the loading-complete dispersion transitions, although several investigators have worked on these two transition stages. Thus, knowledge of the interrelation between these two stages would be of theoretical and practical importance. In this work, the dependence of the stirrer speed at complete dispersion, n CD , on the stirrer speed at flooding, n F , was experimentally studied, in coalescing and non-coalescing systems, using Rushton turbines of two different diameters. The experimental results, having an accuracy of < 5 %, are given in the form of a dimensionless correlation.

The Light Transmission Method as a New Technique for Determining Flooding Characteristics in Gas‐Liquid Contactors

“…(2) is derived by the condition given by Eq. (4), based on research results given in a previous work [1].…”

“…3 and 4 for two different impeller diameters. According to our previous experimental results [1], the firm belief is established that point x o , which here corresponds to the Froude number (or the impeller speed) at the flooding-loading transition, Fr F , is that for which the following mathematical relationships are valid:…”

“…At the flooding-loading transition point the gas holdup increasing rate decreases very sharply, and since the gas-liquid interfacial area needed for the mass transfer is a function of bubble diameter and gas holdup, flooding characteristics are important for getting sufficiently high mass-transfer coefficients. However, only the complete dispersion stage gives efficient dispersion characteristics, in contrast to the flooding and loading stage, for which the whole of the tank is not efficiently used, as it is analyzed in a previous work [1]. In this previous work, an interrelation between flooding stage and complete dispersion stage is given by an equation between Fr F and Fr CD , corresponding to these two dispersion stages.…”

Μελέτη Των Καταστάσεων Πλημμύρισης Σε Αναδευόμενα Συστήματα Αερίου-Υγρού

“…Σχήμα 9.1 Οι μεταβάσεις στην πλημμύριση και στην πλήρη διασπορά για τις δύο διαμέτρους προωθητήρα [46].…”

“…ο συσχετισμός των δύο μεταβάσεων 109 Μεταξύ λοιπόν των δύο μεταβάσεων προκύπτει πως ισχύει η συσχέτιση [46]:…”