Influência da velocidade de aquecimento e da temperatura final de carbonização nas propriedades energéticas do carvão vegetal do lenho e da casca de vernonanthura phosphorica

Abstract

The present study aims to evaluate the influence of the heating rate and the final carbonization temperature on the energetic properties of charcoal obtained from the wood and bark of Vernonanthura phosphorica, an invasive species. To achieve this objective, an experimental study was carried out in which a 3 cm thick disc was removed from the DBH region of five towers obtained from the same number of trees of the species to determine the basic density of the wood and bark. The bark was removed from the remaining material of the tower and approximately 260 0.5 cm thick discs were produced for carbonization and subsequent determination of the gravimetric yield and immediate chemical analysis of the charcoal. The wood and bark samples were subjected to different carbonization conditions in a muffle furnace at temperatures of 400°C, 450°C, 500°C, 550°C and 600°C. For each temperature, carbonization was performed at heating rates of 1°C/min, 2°C/min and 3°C/min. The results indicate that the average basic density of the Vernonanthura phosphorica wood was 0.47 g/cm³ and of the bark 0.22 g/cm³. The gravimetric yield values ​​ranged from 28.67% to 38.09% for charcoal from the wood and from 33.40% to 48.32% for charcoal from the bark. For the volatile material content, the average values ​​of wood charcoal ranged from 9.25% to 32.01%, and of bark charcoal from 11.27% to 33.77. The ash content ranged from 1.69% to 9.38% for wood charcoal and from 8.49% to 15.30% for bark charcoal, while the fixed carbon content ranged from 65.41% to 86.91% and from 57.41% to 77.30% for wood and bark charcoal, respectively. The results obtained show that both the final temperature and the heating rate significantly influence the energy properties of wood charcoal, as well as bark, which had a higher ash content than wood. However, the carbonization temperature is the factor that deserves greater control in the carbonization process, since it greatly influences the gravimetric yield, the volatile material content, the fixed carbon content and the energy quality of the coal in general.