A novel, energy-efficient, high-intensity dryingprocess will be developed to enhance overall productivity in thepaper making operation. The drying process involves directcontact between a wet paper web and a molten metal heat transferfluid to achieve an order of magnitude increase in the dryingrate compared to conventional evaporative dryers. The molten filmhigh-intensity dryer replaces the complex multi-cylinderapparatus and air handling systems of conventional paper dryerswith a single, integrated, heat exchange device resulting in asignificant reduction in dryer size and cost. Because thehigh-intensity drying process does not depend on the heating oflarge quantities of ventilation air to remove moisture from thepaper machine room, a 10 to 30aJo increase in thermal economy isattained. Prior attempts to achieve high-intensity drying usingheated belts, platens, or press rolls to transfer drying heat tothe paper web have been constrained by limitations in productionspeed, operating flexibility, and product quality. The use ofmolten metal alloys as the thermal drying medium overcomes theselimitations by providing a simplified dynamic method ofhigh-intensity heat input having relevance to a broad spectrum ofdrying applications. Phase I will demonstrate the feasibility ofthe molten film drying cycle, and experimental tests will beconducted to measure heat fluxes and dried paper mechanicalproperties obtained using a dynamic molten film dryer test rig.Phase II will involve engineering development of thehigh-intensity molten film dryer to address critical issues forcommercial scale-up.Anticipated Results/Potential Commercial Applications asdescribed by the awardee: Molten film high-intensity dryingprovides a commercially adaptable method for increasing dryerheat flux, and reduces dryer size, cost and thermal energy consumption. The molten film drying method offers the potentialfor improved fiber strength and surface properties and isapplicable to a wide range of paper related products.
