Entrainment Reduction in a Static-Mixer Settler Setup by Electric Field Enhanced Coalescence

This paper investigates the application of electric field enhanced coalescence for entrainment reduction in a static-mixer settler setup for a caprolactam-toluene-water and an ethylbenzene (EB)-α -methyl benzyl alcohol (MBA)-water systems. The mixing of the organic and aqueous phase was done in a static-mixer and an AC/DC electric field was applied directly at the end of the static-mixer. The drop size and entrainment were measured at different flowrates, with and without the electric field, at a field strength of 0.4 kV/cm and 1 kV/cm, and at frequencies ranging from 3 to 100 Hz. Significant drops coalescence was observed which resulted in 4-5 times less entrainment. The AC field was more efficient than the DC field and an optimum frequency of 3-10 Hz was obtained. Additionally, the role of phase ratio and temperature was examined. For the caprolactam system, the entrainment reduction efficiency increased up to a phase ratio of 10% v/v and decreased again at 20% v/v. For the MBA-EB-water system, the efficiency did not change much between a phase ratio of 5% v/v and 10% v/v but decreased at a phase ratio of 20% v/v. Furthermore, entrainment decreased at high temperature for the MBA-EB-water system. However, it increased for the caprolactam-toluene-water system.