Abstract Mechanical dewatering and thermal techniques were evaluated as pre-treatment steps to reduce the water content of spent coffee ground (SCG) powders to thermal conversion. An exploratory evaluation of the fluid dynamic patterns in fluidization of wet SCG powders showed that stable fluidized regimes were achieved with powders of moisture levels under 50 %. Mechanical dewatering was effective to reduce the powder moisture content to 45 %. Adding vibration enhanced the powder feed rate in the drying bed, even for powders with moisture levels that lead to negligible cohesiveness. Using a dimensionless vibration number Γ = 4 with different vibration amplitudes (A = 0.015 and 0.003 m) resulted in different dynamic behaviors and influenced the solids feeding rate but did not affect the mean Sauter diameter of the elutriated powder. Thermal drying at Γ = 4 and A = 0.015 m allowed a steady and continuous operating regime for powder production. Under these vibration parameters, the optimum condition concerning moisture content (22 % w.b.) and mean particle size (0.37 mm) was predicted to occur at 70 °C, and U/Umf = 6. The dry powder was thermally characterized and confirmed the feasibility of using this residue in pyrolysis and combustion processes. The parameters of the reaction kinetic model and the apparent specific heat were obtained.

中文翻译：

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处理废咖啡粉以产生可再生能源：机械脱水和热干燥

摘要 机械脱水和热技术被评估为预处理步骤，以减少废咖啡渣 (SCG) 粉末的水含量以进行热转化。对湿 SCG 粉末流化过程中流体动力学模式的探索性评估表明，使用水分含量低于 50% 的粉末可实现稳定的流化状态。机械脱水可有效地将粉末水分含量降低到 45%。增加振动可提高干燥床中的粉末进料速度，即使是对于水分含量导致内聚性可忽略不计的粉末也是如此。使用具有不同振幅（A = 0.015 和 0.003 m）的无量纲振动数 Γ = 4 会导致不同的动态行为并影响固体进料速率，但不影响淘析粉末的平均 Sauter 直径。Γ = 4 和 A = 0.015 m 的热干燥允许粉末生产的稳定和连续操作制度。在这些振动参数下，关于水分含量 (22 % wb) 和平均粒径 (0.37 mm) 的最佳条件预计发生在 70 °C 和 U/Umf = 6。干粉经过热表征并证实了可行性在热解和燃烧过程中使用这种残留物。得到了反应动力学模型的参数和表观比热。对干粉进行了热表征，并证实了在热解和燃烧过程中使用这种残留物的可行性。得到了反应动力学模型的参数和表观比热。对干粉进行了热表征，并证实了在热解和燃烧过程中使用这种残留物的可行性。得到了反应动力学模型的参数和表观比热。