Estudo comparativo do potencial energético do juazeiro (Ziziphus joazeiro Martius) e da algarobeira (Prosopis juliflora (Sw.) DC.) na produção de carvão no Semiárido Paraibano.

Abstract

The caatinga vegetation is the major vegetational component of the state of Paraiba, covering about 80% of its territory. There is a large dependence of the population and other sectors of the economy in relation to its forest product as an energy source, which represents between 30% and 50% of primary energy. This study aims to determine the energetic potential of the coal from Ziziphus joazeiro (Martius) and Prosopis juliflora (Sw.) DC., improving information on tree species which occur in the Brazilian Northeast semi arid. Dendrometric parameters were evaluated, such as total and commercial height, diameter at breast height (DBH), the volume with and without bark. After wood carbonization, were determined the energetic characteristics of coal from the studied species, such as higher calorific value, gravimetric yield, true and apparent density, porosity, condensed product yield and immediate chemical analysis (moisture content, volatile materials and ashes). The Prosopis juliflora showed higher values, exceeding the ones from Ziziphus joazeiro and those from the others correlated tree species. Both species showed a great potential for the production of charcoal, taking into account its excellent levels of gravimetric yield, fixed carbon and calorific value. The species Ziziphus joazeiro showed significant positive correlations between the average basic density parameters and the condensable liquid yield, fixed carbon and holocellulose and also the wood and ashes gravimetric yield vs. volatile matter, and negative and significant factors between the holocellulose content and total lignin, condensable liquid yield and apparent density, total lignin and fixed carbon and fixed carbon and volatile matter. Concerning Prosopis juliflora species, it was observed significant and positive correlations showed for the total extractive contents and wood calorific values, true density and gravimetric yield, fixed carbon and volatile matter, gravimetric yield and coal calorific values. It was observed only a negative correlation between the holocellulose levels and total extractive.