Mechanical strength characterisation of pyrolysis biochar from woody biomass

Abstract

In order for biochar (which is produced via waste wood pyrolysis) to be used in sustainable energy or material production, it is crucial to determine certain properties, such as its mechanical strength. Consequently, in this paper, municipal waste wood (MWW)11Municipal waste wood. and forestry residue biomass (FRB)22Forestry residue biomass. – as a point of reference – are examined in an autothermal pyrolysis unit. The mechanical strength of the biochar is analysed via an uniaxial compression experiment. The present paper proposes an advanced method to investigate the strength of pyrolysed biochar in a representative and comprehensive manner, since no standards are available in literature. It has been found that firstly, the mechanical biochar’s strength decreases with increasing temperature, and secondly, that biochar prepared from FRB shows a higher breaking strength than biochar produced from MWW. Furthermore, an approximately linear progression between degree of pyrolysis and the mechanical strength is observable. Successful experiments on the gasification of MWW confirm the results obtained in this study. Additional allothermal pyrolysis experiments reveal higher strength values and reflect the more precise temperature adjustment. These results can be used as a point of reference in future research on alternative biogenic energy carriers and biochar products.