Biocarbon pellet production: Optimization of pelletizing process

Biocarbon is charcoal produced as a by-product of fast pyrolysis and gasification or as the main product of slow pyrolysis. The biocarbon can be used as a fuel in combustion systems both at large scale and small scale. The University of Perugia is collaborating with SINTEF IN Norway regarding biocarbon combustion tests in pellet boilers, adapting the fuel and the air mass flows to the new fuel. Overall, the two critical aspects are: 1) the production of pellet from biocarbon and 2) its combustion performance in small boilers. The objective of the work is to optimize biocarbon pellet production. To produce this new kind of pellet the moisture content and the use of additives have to be carefully adjusted and optimized. A Box-Behnken experimental scheme has been used for this purpose. It was implemented in the software Minitab 17. Fifteen pelletization tests have been performed with mixtures of biocarbon, sawdust and water in different proportions. The durability of the obtained pellet was measured. The optimal mixture was found to be: 30%w/w moisture, 30%w/w sawdust and 40%w/w biochar. The obtained pellet had both higher durability and heating value (23,057 kJ/kg).6s