You are here:
Membrane-assisted vapor stripping: energy efficient hybrid distillation-vapor permeation process for alcohol-water separation
Citation:
VANE, L. M. AND F. R. ALVAREZ. Membrane-assisted vapor stripping: energy efficient hybrid distillation-vapor permeation process for alcohol-water separation. J Melling (ed.), Journal of Chemical Technology and Biotechnology. John Wiley and Sons, LTD, , Uk, 83(9):1275-1287, (2008).
Impact/Purpose:
information
Description:
BACKGROUND: Energy efficient alternatives to distillation for alcohol recovery from dilute solution are needed to improve biofuel sustainability. A process integrating steam stripping with a vapor compression step and a vapor permeation membrane separation step is proposed. The objective of this work is to estimate the energy and process costs required to make a fuel grade ethanol (0.5 wt% water) from 1 and 5 wt% ethanol aqueous streams using the proposed process. RESULTS: Using process simulation and spreadsheeting software, the proposed membrane assisted column stripping process was estimated to require as little as 8.9 and 2.5 MJ of fuel-equivalent energy per kg of fuel grade ethanol recovered for 1 and 5 wt% ethanol feed streams, respectively. This represents an energy savings of at least 43% relative to standard distillation producing azeotropic ethanol (6 wt% water). Process costs were also found to be lower than for distillation at the 3.0×106 kg-ethanol/yr scale modeled. CONCLUSION: In this hybrid system, the stripping column provides high ethanol recoveries and low effluent concentrations while the vapor compression-membrane component enables the efficient recovery of latent and sensible heat from both the retentate and permeate streams from the membrane system.
