Browsing by Subject "carbonization"

Carbonization is thermochemical conversion, where biomass is thermally degraded in the absence of oxygen. Solid char, pyrolysis oil and non-condensable gases are produced from the biomass. Torrefaction is early phase of the carbonization in temperatures of 220–300 °C. Torrefied wood is promising as a renewable fuel for industrial use in coal co-combustion and gasification-combustion. Torrefaction and carbonization increase the higher heating value and fuel properties of wood compared to untreated wood. There’s a lack of knowledge in torrefaction and carbonization effects to higher heating value, carbon content and turn from endothermic to exothermic reaction of conifer zone wood species. Raw material was stemwood of birch (Betula pubescens) and pine (Pinus sylvestris) including bark. Trees were harvested from the Helsinki district and chipped, particle size 16 ? 8 mm. Samples were torrefied and carbonized at 250, 300, 350, 400 and 450 ?C without nitrogen flow. Carbon content (%), higher heating value (MJ/kg), mass yield (%) and turn of endothermic to exothermic reaction were inspected. Carbon content of untreated birch and pine increased from 47 % to 82 % (at 450 ?C). Higher heating value exceeded 26 MJ/kg at 300 ?C and 28 MJ/kg at 400 ?C, reaching bituminous coal’s values. Mass yield declined to 45–54 % of the initial mass at 300 °C. In low temperature, gradual exothermic peak was observable. In higher temperatures peak was evident. Carbonization and torrefaction improved the higher heating value and carbon content of wood but decreased the solid char yield.