EUCALYPTUS LOGS DRYING AT HIGH TEMPERATURES

ABSTRACT The objective of this work was to evaluate the drying speed of Eucalyptus urophylla logs in high temperatures and the influence of the presence or absence of bark and also the diameter of the log in the drying rate. Eucalyptus logs 60 cm long were divided into three diameter classes: 8-12 cm; 12,1-16 cm and 16,1-20 cm. The logs were dried in a heater with forced air circulation, in the presence or absence of bark in five temperatures: 50, 75, 100, 125 and 150ºC. The mass and the initial moisture were determined from each log and the water loss was kept up with periodic weightings, closing the drying process when the logs reached 20% moisture. The drying rate of the logs was calculated using the ratio between the total loss of moisture and the time in hours in order to reach the established moisture. It was concluded that the increase in temperature promotes the raise of the drying ratio, as being higher for smaller logs in relation to bigger ones and in addition to this, the bark effect was not significant in the drying of eucalyptus logs above 100ºC. It was also concluded that the best conditions for the operation of artificial dryers for Eucalyptus logs containing bark and separated in diameter classes would be at 125ºC.