Pyro-gasification of hazelnut pruning using a downdraft gasifier for concurrent production of syngas and biochar

Hazelnut pruning constitute a waste management problem with critical environmental consequences, in fact the most common solution taken into account by farmers for hazelnut pruning management consists in an uncontrolled outdoors combustion in field that causes toxic gaseous emissions. The aim of this work is to provide an alternative solution represented by use of pruning as feedstock in a downdraft air gasifier, working with low values of equivalence ratio (ER), in order to obtain syngas and biochar. In this study, chips of shredded hazelnut pruning with a lower heating value (LHV) of about 15,3 MJ/kg and a moisture of 15% have been used. Syngas obtained shows an LHV increasing from 3,84 to 4,45 MJ/Nm with the rise of airflow introduced. Char coming from the pyrolysis of biomass shows an high carbon content of about 75% while the solid residue, that is the biochar resulting from the partial gasification of char of pyrolysis, is characterized by a carbon content ranging from about 32% up to 47% for the higher and lower airflow values respectively. Results show that the energetic value of syngas is suitable for heat and power production while biochar can be used as soil improver and carbon sink. 1340 Andrea Colantoni et al.