Micro-Scale Liquid-Liquid Separation in a Plate-Type Coalescer
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Intensified Hydrodynamics & Structured Environments (IHSE-4)
Keywords: Microprocess, Liquid-liquid separation, Extraction, Coalescer
Eero Kolehmainen*, Ilkka Turunen
Lappeenranta University of Technology, Department of Chemical Technology, Product and Process Development, P.O Box 20, FIN-53851 Lappeenranta, Finland
Keywords: Microprocess, Liquid-liquid separation, Extraction, Coalescer
Introduction
Microprocess technology represents process intensification at its extreme eliminating the extra heat and mass transfer limitations in chemical processing. Several applications of microreactors have been presented for chemical reactions, but still microprocesses for separation purposes are rare. In micro-scale extraction processes, efficient separation step for immiscible liquid streams is important. The aim of this study was to develop and test so-called plate-type coalescer for continuous separation of immiscible liquid streams. The method is based on the difference in wetting properties of materials. Aqueous and organic liquids have different contact angles on surfaces. This feature leads to velocity difference between liquid phases in the coalescer and liquid droplets start to coalesce.
Experimental set-up
The coalescer consisted of two plates. The used materials were stainless steel, PTFE and glass. A rectangular flat channel was machined on the surface of the other plate and the channel was situated between the plates. The dimensions of the channel in the coalescer were as follows: width 15 mm, length 200 mm, height 0.10 mm and 0.20 mm. In the experiments, dispersion was achieved by feeding the immiscible fluids through the slit interdigital micromixer. The micromixer was connected to the coalescer, where coalescence of the liquid droplets took place.
Results
Results showed that high separation efficiencies could be achieved in the plate-type coalescer. Separation efficiency is defined on the basis of the component concentration in the influent and the effluent. Water and Shellsol-solvent were the immiscible liquids. Separation efficiency was studied with respect to surface material of the plates, channel height, fluid composition, average fluid velocity and droplet sizes. High separation efficiencies, up to 99 %, were obtained by using stainless steel and PTFE plates. Average fluid velocity and droplet sizes had a notable effect on separation efficiency.
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Presented Thursday 20, 11:40 to 12:00, in session EPIC-1: Intensified Hydrodynamics & Structured Environments (IHSE-4).
