NSF Award
9961229
This Small Business Innovation Research (SBIR) Phase I project will develop closed-loop solvent evaporation ovens. Currently, industrial processes pass large.volumes of heated air through the evaporation oven, producing an air stream effluent contaminated by volatile organic carbon (VOC) compounds. These present environmental problems and no opportunity for recovery of the solvent. The proposed process is an enclosed, closed-loop system using nitrogen as the recirculating gas and a membrane to recover the evaporated solvent vapors and remove oxygen and water vapor derived from air that leaks into the gas. The amount of make-up nitrogen required will be small. Operating costs would be justified by the avoided costs of treating the dilute VOC-contaminated air stream and by the value of the recovered solvent. The main Phase I experimental task involves a selection of an oxygen-permeable, solvent vapor/nitrogen-impermeable membrane for the oxygen removal step. The membrane must retain these properties at high solvent vapor pressures and high feed gas temperatures. A prototype of the system will also be designed and the construction costs estimated. Phase II will build a complete system and operate it in the laboratory and at cooperating host sites to evaluate process benefits and costs.<br/><br/>Replacement of direct-air-vented solvent evaporation ovens with affordable closed-loop nitrogen recirculation systems would become feasible for use in tablet coating and printing operations, preparation of tapes and adhesive films, and surface coating, varnishing, and painting operations common in industry. The new oven systems will allow solvent recovery and reuse, eliminate troublesome vapor emissiona, and offer many processing advantages. Affordable systems based on this technology are expected to be widely used.
