Abstract:
Extraction processes usually have relatively low productivity in batch operation and back-mixing problems in countercurrent continuous operation. An operation method of alternating feeding between light and heavy phases (AFLHP) was proposed to solve these problems. Mass transfer in a perforated-plate extraction column via AFLHP was experimentally studied using a kerosene-benzoic acid-water system. The overall mass transfer coefficient based on dispersed phase (
Kod>) was obtained using the single drops model. Effects of operational parameters such as rising velocity of droplets, plate spacing and flow rates of dispersed and continuous phases on overall mass transfer coefficient were investigated. The results show that the values of
Kod> range from 3.49×10
-5 to 5.47×10
-5 m·s
-1, which indicates that the AFLHP perforated-plate extraction column significantly reduces back-mixing and outperforms Kühni extraction column, pulsed extraction column and rotating disc columns. Furthermore, the values of total dispersed phase hold-up are between 1.63% and 4.37%, which means that flooding is unlikely in the AFLHP perforated-plate extraction column.