WET LINE EXTENSION REDUCES VOCS FROM SOFTWOOD DRYING

VOC emissions from drying softwood oriented strand board (OSB) furnish or particle increase with decreasing particle size and with increasin g oven temperature and airflow rate. The surface area is related to pa rticle size; hence, a decrease in size preferentially dries out the su rface. Similarly, drying at high temperature or under high airflow dep letes surface moisture. VOCs from dried particle increase sharply beyo nd 160 degrees C. The optimum drying strategy from the perspective of reducing VOCs should minimize temperature imbalances and moisture grad ients within the flake in order to reduce dry spots. Since surface dry -out will impede the movement of, water to the surface, its onset shou ld 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.