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

Abstract

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.

Keywords:

• coalescence
• electric-field
• entrainment
• frequency
• static-mixer

ACKNOWLEDGEMENTS

ISPT is gratefully acknowledged. The authors would like to acknowledge Katarina Babic from DSM for valuable suggestions on the paper, and Wouter Hoek from Lyondell Chemie B.V. for providing information regarding the industrial propylene oxide-styrene monomer process.

Notes

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