HIGH-TEMPERATURE DRYING OF WOOD SEMIINDUSTRIAL KILN EXPERIMENTS

We briefly introduce the main results obtained in our laboratory about high temperature drying kinetic of softwood and hardwood. We point out during drying the acceleration effect of pressure gradient in vapour phase which develops in the wood. Then we give the main experimental results carried out on a small industrial kiln which can dry wood boards with moist air and superheated steam at high temperature till 180°C and velocity above to 6 m/s. The drying process is completely automated. Tested species are : beech, poplar, fir and maritime pine. We show that the drying kinetics are almost the same using the industrial kiln or the wind tunnel and we define for different board thicknesses, temperatures and velocities the optimal sequences of the process. The influence on the quality of the pretreatment, the various drying periods and the post-steaming is of importance. © 1990, Taylor & Francis Group, LLC. All rights reserved.