Optimization of pine sawdust densified biofuel: Effects of process parameters on fuel quality and temperature distribution

The valorization of forestry waste into densified biofuels is critical for sustainable energy development. This study investigates the optimization of the densification process for pine sawdust by examining the effects of key parameters on the final product quality, specifically focusing on the uniformity of the internal temperature field. A four-factor, mixed-level orthogonal experiment was designed, investigating forming pressure, moisture content, binder addition ratio, and heating temperature. The temperature mean square deviation (MSD) was utilized as the primary response variable to quantify thermal distribution uniformity. Analysis of variance (ANOVA) was performed to determine the statistical significance of each factor, and a multivariate regression model was established. Results from ANOVA indicated that the descending order of significance for factors impacting temperature MSD was: moisture content > forming pressure > heating temperature > binder addition ratio. A statistically significant interaction effect was identified between forming pressure and heating temperature. Response surface methodology was employed to optimize these two significant factors. The optimal conditions for minimizing temperature MSD, while maintaining constant moisture content and binder ratio, were determined to be a forming pressure of 10 MPa and a heating temperature of 190°C. By optimizing process parameters to achieve a more uniform temperature field, the quality and stability of the resulting pine sawdust densified fuel were significantly improved. This work provides a quantitative theoretical basis and key technical parameters for the scale-up and industrial application of biomass fuels in boilers and residential heating systems, thereby promoting the development of a low-carbon circular economy.