Wet Line Extension Reduces VOCs from Softwood Drying

Abstract

VOC emissions from drying softwood oriented strand board (OSB) furnish or particle increase with decreasing particle size and with increasing oven temperature and airflow rate. The surface area is related to particle size; hence, a decrease in size preferentially dries out the surface. Similarly, drying at high temperature or under high airflow depletes surface moisture. VOCs from dried particle increase sharply beyond 160 °C. The optimum drying strategy from the perspective of reducing VOCs should minimize temperature imbalances and moisture gradients within the flake in order to reduce dry spots. Since surface dry-out will impede the movement of water to the surface, its onset should be delayed. Hence, the wet line should be maintained at the surface for as long as possible to keep the furnish evenly wet during drying.