Caracterização e estudo termogravimétrico da pirólise e da combustão da casca de pinhão visando seu aproveitamento energético

Abstract

With the accelerated increase in energy demand, and the predominance of non-renewable fossil fuels in the matrix, biomass has been studied to meet this demand, producing more energy with less environmental impact. In this context, the objective of this work was to investigate the energy potential of a pine nut shell sample (Araucaria angustifolia) with particles smaller than 300 μm, through physical-chemical analysis, such as apparent density, proximate analysis, elemental analysis, and higher calorific value, and through thermogravimetric analyzes in an inert and oxidizing atmosphere, using heating rates of 10, 15, 25 and 40 °C/min, from room temperature up to 900 °C. Pine nut shell proved to be a low-cost biomass for storage, handling, and transport, through its relatively high apparent density (333.12 ± 7.55 kg/m³). Low constents of moisture (8.16%), ash (1.18%), nitrogen (0.76%) and sulfur (null), and high volatile matter content (66.10%), were desirable for generating bioenergy from thermochemical conversion processes. The high heating value obtained experimentally was 16.79 MJ/kg, proving the potential of the pine nut shell as a biofuel. Also, from the Van Krevelen diagram (atomic molar ratios H/C as a function of O/C), it was possible to compare the energy content of the residue studied with other biomasses and mineral coals available in the literature. From the thermogravimetry curves and their derivative, it was possible to identify the mass losses and the temperature ranges of degradation of the major components of the biomass (hemicellulose, cellulose and lignin), and the characteristic temperatures of the pine nut shell combustion process were also determined. Furthermore, it was possible to compare the processes of pyrolysis and combustion, and to evaluate the best conditions for using biomass. It was concluded that the pine nut shell has a great energy potential and can be used as an alternative and renewable source in the generation of bioenergy, through thermochemical conversion processes of pyrolysis and combustion.