Abstract:The purpose of this study is to reduce the energy consumption in the process of biomass pellet fuel from medicine residues of ginkgo biloba. The main processing links of biomass pellet fuel included the drying, pulverization, and granulation molding. The unit energy consumption in each procedure during processing was evaluated using the physical experiments. First, the medicine residue of ginkgo biloba was dried at a constant temperature of 60-120 ℃ hot air to a moisture content of 20%. An evaluation was performed on the influence of different drying temperatures on the drying energy consumption. Then, orthogonal experiments were utilized to consider the effect of moisture content, screen aperture, and spindle speed on the unit energy consumption of pulverizing. A systematic analysis was also made on the effect of moisture content and particle size on the energy consumption during granulation and molding. Finally, the optimal conditions of process parameters were determined to fabricate the biomass pellet fuel using medicine residues of ginkgo biloba. A specific ratio was defined as the calorific value of produced pellet fuel to the total processing energy consumption. The test results showed that the unit drying energy consumption was the lowest at a drying temperature of 110 ℃. In pulverizing, the unit energy consumption was the lowest under the conditions that the moisture content of raw material was 13%, the screen aperture was 4mm, and the spindle speed of pulverizer was 4 550 r/min. In granulation molding, the unit energy consumption was the lowest, when the particle size was 4 mm, while the moisture content of raw material was 16%. Considering the specific ratio, the optimal process parameters to prepare the biomass pellet fuel from medicine residue of ginkgo biloba were as follows: the drying temperature was 110 ℃, the moisture content of raw material was 16%, the screen aperture was 3 mm, and the spindle speed of the pulverizer was 4 550 r/min. Under this processing condition, the total energy consumption per unit was 4 478.3 kJ/kg, and the unit calorific value of the produced pellet fuel was 17 352.4 kJ/kg, indicating well matching to the national technical standards for biomass solid briquette fuel.