Abstract
In the present study, a new upgrading solid biofuel, “torrefied wood briquette” that is utilized as co-firing fuels in coal-fueled power plants is proposed. The “torrefied wood briquette” is produced by the torrefaction and compression molding processes to enhance the apparent density and heating value of solid biofuel. To clarify the optimum molding conditions for torrefied woody biomass to mold high density briquettes, experimental studies are conducted on thermo-fluid phenomena and compression molding of torrefied woody biomass. The following results are obtained. (1) The softening temperature increases with decreasing mass yield, water content and pressure. Comparing the two biomass species, the softening temperatures for Japanese cedar are higher than those for pruned sprig of persimmon. (2) The apparent density of briquette has a maximum when the compression molding is conducted at the softening temperature for given mass yield and water content. The torrefaction process gives the trade-off relationship between the heating value and apparent density of torrefied wood briquette.
