Hybrid Membrane Distillation Process for Enhanced Integrated Ethanol Production

The conversion of corn and other biomass to fuel grade ethanol not only would reduce U.S. dependence on foreign energy sources but also would be a major industrial application for agricultural products. However, the process of drying the ethanol to fuel grade consumes significant amounts of energy, incurring costs that continue to increase as cost of natural gas increases. This project will develop technology for introducing a hybrid membrane distillation process that will significantly reduce both the energy and capital requirements for drying. Phase I demonstrated that the membrane technology could preferentially remove water from water-ethanol azeotrope and produce fuel grade ethanol (FGE). The membranes were shown to operate at high temperature (130oC) and high pressure (200 psia) while providing high flux, high separation, excellent chemical resistance, and long term stability. An engineering and economic model demonstrated that the membrane modules could provide major savings in both capital costs ($0.7 versus $4.2 million) and energy consumption (33 ¿ 239 billion BTU/yr) for a typical 70 million gallon/yr ethanol plant, compared to conventional molecular-sieve driers. In Phase II, both prototype laboratory systems and field test systems will be built and evaluated. Participation by ethanol design firms will facilitate field testing and subsequent engineering and economic analysis.Commercial Applications and other Benefits as described by the awardee: The intial target market for this technology is the growing 13 billion gallon/year ethanol business. The technology also should be applicable to many other energy intensive separation processes