Effects of poplar f ibres as solid bridge on the physical characteristics of biomass briquette made from sawdust and bamboo powder
At room temperature, on condition that the die be within temperatures of 200 – 300°C biomass briquette production made from sawdust (S) and bamboo powder (B) was conducted by a briquette extruder using post-heating method, fibre with steam explosion poplar fibres used as additive. As observed through the microscope, fibres as additive has the micro-mechanism of promoting mechanical properties of biomass briquette during densification. For verifying the feasibility and effect of fibre as additive, BBD experimental design was macroscopically adopted to compare the indicators of surface quality, relaxation density, maximum radial compression pressure, and hydrophobicity. Response surface model was used to deduce the reasonable heating temperature range for exploring the suitable condition of fibre as additive. The result showed that fibre as additive has apparent effect on briquette densification of sawdust and bamboo powder within a given temperature range. Through microscopic observation, it was found that fibres acted as solid bridges which played a positive role in densification in the heating temperature of 200∼250°C. At the temperature of 240°C, the fibres started to be carbonized. And within the temperature range of 250-300°C, the carbonized fibre mainly acts as lubricant between the briquette and the channel surface of the die.