Numerical simulations of liquid-liquid flow in a continuous gravity settler using OpenFOAM and experimental verification

Abstract

In several applications involving solvent extraction, crude oil processing, hydrometallurgical operations; separation of liquid-liquid dispersions is a challenging task. In the present work, we report numerical simulations of liquid-liquid flow in a continuous gravity settler and their experimental validation. The twoPhaseEulerFoam module available in open source CFD code OpenFOAM was developed further to simulate three-phase flow of aqueous and organic phases in a continuous gravity settler with free gas region at top (freeboard region). The predicted dispersion band thickness and spatial variation of organic phase volume fraction were verified using the measurements performed in a laboratory-scale settler. While the measured and predicted dispersion band thickness agreed well, owing to the constant drop size considered in the present work, the predicted organic phase volume fraction was found to be lower than the measurements. The effects of liquid flow rate, drop diameter, inlet baffle position and organic phase density were investigated. With the increase in drop diameter, interestingly, it was found that the dispersion band thickness was reduced and significant fluctuations in the local organic phase volume fraction were observed. The fluctuations were found to decrease with increase in the total liquid flow rate. The experimentally validated computational model will be useful in designing large-scale continuous gravity settlers and optimize their separation performance.