Charcoal in a Nutshell: Biocarbon Production from Cellulose, Norwegian Wood, Macadamia Nutshells and Sewage Sludge

Abstract

While progressively diminishing our reliance on fossil fuels, it is of paramount importance to keep advancing low-carbon economic growth. A crucial role can be played by clean and efficient flash carbonization of biomass into biocarbon. This thesis reviews several elevated-pressure flash carbonization experiments, pyrolyzing varying biomass feed stocks and using different types of reactors. Renewed Lab-scale sewage sludge carbonization experiments were intended to remedy shortcomings with respect to the experimental reproducibility and inaccurate analyses of heavy metal concentrations that have come to light in our previous work on sewage sludge carbonization. In support of the Norwegian ferrosilicon industry, local birch, spruce and GROT were carbonized in the lab-scale reactor, with a view to analyzing the impact of pressure, soft versus hard wood and FC canister insulation on their respective fixed carbon yields. Demo-scale reactor macadamia nutshell carbonization experiments (creating charcoal with fixed carbon contents of 97%) taught us how to avoid fumes from being emitted and to better monitor the self-designed thermal afterburner. Avicel cellulose carbonization experiments conducted under varying elevated pressures in the upgraded Wall-Heated Tubing Bomb Reactor produced, while showing evidence of a molten phase, high-quality solid pieces of charcoal. They enabled us to achieve 98% of the theoretical fC yield of cellulose.