Pressurized hot water treatment of sugar maple and yellow birch wood particles for high quality fuel pellet production

This study was conducted with the aim of converting low quality hardwoods into high quality fuel pellets by using hot water as a pretreatment method. Hardwood particles from sugar maple and yellow birch trees were first pretreated with hot water at 150 °C, 175 °C and 200 °C for 30 min in a batch reactor. The solid fractions following hot water treatment were then compacted into pellets using a single pelletizer. The produced pellets exhibited a number of enhanced properties as compared to those obtained from untreated wood particles. The increases in density and energy content of pellets reached approximately 30% and 40%, respectively. Compressive strength was increased by three times or more. Results also indicated that pellets of high water resistance were obtained using material treated with hot water at a temperature of about 200 °C for both sugar maple and yellow birch wood. In addition, considerable reduction in friction in the die was observed when treated wood particles were used.