Torrefaction of Flax Shives as a Process of Preparation Waste Vegetable Biomass for Energy Purposes

The use of processed biomass, derived from agricultural crop residues, as a fuel is becoming increasingly important in the energy sector, which additionally allows for the management of excess waste that is a burden on the environment. The aim of this study was to investigate the effect of the torrefaction process conditions in a carbon dioxide atmosphere on the chemical structure of biocarbon and the energy parameters of the produced product, which can be a solid biofuel. The biomass chosen for the experimental work was flax shive. Determinations of the heat of combustion of the produced biocarbon samples were carried out using a KL-10 calorimeter, and identification of the molecular structure of the product and the starting biomass was carried out using infrared spectrometry. It was confirmed that increasing the temperature of biomass torrefaction increases the heat of combustion of the product, with this parameter obtaining the most favourable value for biocarbon obtained during torrefaction at 320°C and for 20 to 30 minutes. The heat of combustion of the biocarbon produced during torrefaction at 320°C and for 30 minutes was 25.92 MJ/kg, with a feedstock mass loss of 41%. Such conditions lead to a significant conversion of the chemical structure of the biomass, with no complete destruction of organic structures.