Biochars Produced from Pressurized Torrefaction: Fuel Properties and Combustion Behaviour

In this paper, the pressurized torrefaction (PT) of miscanthus and the combustion behaviour of the torrefied products were investigated.The torrefaction reactions were conducted in a 600 cm 3 batch autoclave reactor with the operating conditions of temperature, pressure and time varied from 200-300 o C, 10-30 bars and 20-60 minutes, respectively.The key performance metrics of volatile matter reduction, oxygen removal, higher heating value (HHV) enhancement, carbon enrichment and mass/energy yields were evaluated.Our study reported a 4-50% reduction in volatile matter, 4-68% carbon enrichment and a 2-70% oxygen removal in the produced biochars.Furthermore, the higher heating value (HHV) of the biochar ranged from 19.30 0.23 MJ/kg to 34.94 0.65 MJ/kg compared to the raw biomass of 18.86 0.02 MJ/kg.With respect to the influence of pressure, it was found that pressure and secondary reactions played a contributory role in chemical energy preservation, thus leading to high energy yield in the pressurized torrefaction process.Lastly, the derived biochars demonstrated improved characteristics with respect to ignition and burnout temperatures as well as overall combustion performance indices.