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SEPARATION OF VAPOR-PHASE ALCOHOL/WATER MIXTURES VIA FRACTIONAL CONDENSATION USING A PILOT-SCALE DEPHLEGMATOR: ENHANCEMENT OF THE PREVAPORATION PROCESS SEPARATION FACTOR
Citation:
Vane*, L M., F R. Alvarez*, A. Mairal, AND R. W. Baker. SEPARATION OF VAPOR-PHASE ALCOHOL/WATER MIXTURES VIA FRACTIONAL CONDENSATION USING A PILOT-SCALE DEPHLEGMATOR: ENHANCEMENT OF THE PREVAPORATION PROCESS SEPARATION FACTOR. Paul, D.R. (ed.), INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH. American Chemical Society, Washington, DC, 43(1):173-183, (2004).
Description:
In prevaporation, a liquid mixture contacts a membrane surface that preferentially permeates one of the liquid components as a vapor. Our approach to improving pervaporation performance is to replace the one-stage condenser traditionally used to condense the permeate with a fractionating condenser called a dephlegmator. For example, pervaporation of 5 wt% aqueous ethanol yields a vapor containing 35 wt% ethanol. The separation factor for the process is 10. Condensation of this vapor in a dephlegmator yields a vapor product stream containing 90% of the permeating ethanol at a concentration of 85 wt% ethanol. The net result of the combined pervaporation-dephlegmation process is to transform the 5 wt% ethanol feed into an 85 wt% ethanol condensed product. For the overall process, the separation factor has increased 11-fold to 108. Pilot-scale parametric experiments were performed with a plate-fin heat exchanger operated as a dephlegmator. The process was modeled with commercial process simulation software; good agreement between the model and the pilot results was obtained.