Autothermal Siberian Pine Nutshell Pyrolysis Maintained by Exothermic Reactions

Abstract

The global energy industry works towards an increased use of carbon-neutral biomass. Nutshell represents a regional bio-waste, i.e., a bio-energy resource. Pyrolysis is a common method for processing biomass into valuable energy products. The heat demand, however, limits pyrolysis applications. Yet, such demand may be addressed via exothermic pyrolysis reactions under selected operation conditions. Making the pyrolysis of Siberian pine nutshell autothermic comprised the objective of the study. The study involved analytical methods together with a pyrolysis experiment. The analytical methods included a thermogravimetric analysis combined with differential scanning calorimetry and an integrated gas analyzer. Thermophysical characterization was executed using a thermal diffusivity analyzer with the laser flash method. At 650 °C, pyrolytic heat was released in the amount of 1224.6 kJ/kg, exceeding the heat demand of 1179.5 kJ/kg. Pyrolysis at a lower temperature of 550 °C remained endothermic, although the combusted gas product provided 847.7 kJ/kg of heat, which, together with exothermic release, covered the required heat demand for the pyrolysis process.