Variação radial e longitudinal do rendimento gravimétrico de carvão vegetal em clone de eucalipto

Abstract

The gravimetric yield of charcoal depends on the wood and the carbonization process. Intrinsic factors of wood, such as chemical composition, are fundamental in their conversion to coal. Thus, it is expected that both radial and longitudinal variations in the chemical characteristics of wood affect the gravimetric yield in charcoal. The objective of the present work was to evaluate the effect of the radial and longitudinal variation of the wood on the gravimetric yield of charcoal in eucalyptus clone, besides the effect of the diametric class. A clone of eucalyptus, from commercial planting with spacing of 3 m x 2 m and at six years of age, was used in the research. Thirty-four trees were selected in three diametric classes. The longitudinal sampling consisted of the removal of 3 cm thick discs at 2, 10, 30 and 70% of the commercial height of the stem considered until the minimum diameter of 5 cm with bark. The radial sampling consisted of samples being taken at 20, 50, 70, 80, and 90% of the radius, considering the direction of the marrow to the shell. The samples were carbonized in an electric oven using 100 ° C, 450 ° C and 100 ° C minute-1, respectively, as initial temperature, final temperature and heating rate, residence time of 30 minutes and total time of 4 hours. The results showed that the gravimetric charcoal yield was higher in the more basal portions in the shaft of the trees and in the positions closest to the marrow in all diametric grades. The largest diameter class presented, in general, the highest gravimetric yields of charcoal.