Densification is the most effective forming technology, the production of which, pellets are the most intensive energy content of biomass solid fuels. Increasing the overall utilization efficiency of bioenergy, extending available types of wastes and residues for pelleting, and improving the pellet quality comprehensively are necessary. This paper reviewed feedstocks used for pelleting, binding mechanism of biomass pellets, and evaluation systems of pellet qualities. To extend the supply amounts and improve the qualities of raw biomass, various feedstocks and formulation recipes were classified based on their regions, sources, and species. And applicable objects and conditions of several different pretreatment technologies for feedstocks were compared. Physical properties and biochemical analyses are also concluded to evaluate the flowability, compactibility, and potential characteristics as solid fuel. For a better understanding of energy consumption and conversion during the densification process, pelleting devices and binding mechanism are elaborated. Associations and differences between single pelleting press in lab-scale and industrial pelleting in pilot-scale are also discussed. Suggestions are proposed for the optimization design of pelleting devices and processes for different feedstock densification. Lastly, relationships between operating parameter factors of pelleting process and pellet quality are presented. This review could provide theoretical analyses for powder compression, new insights for waste to energy, and guidance for achieving global peak carbon and environmental strategic objectives.

中文翻译：

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从原材料粉末到固体燃料颗粒：生物质致密化的最先进回顾


致密化是最有效的成型技术，其生产的颗粒是生物质固体燃料中能量含量最高的。提高生物能源综合利用效率，扩大废渣制粒利用种类，全面提高颗粒质量。本文综述了制粒原料、生物质颗粒的结合机制以及颗粒质量评价体系。为了扩大供应量并提高原始生物质的质量，各种原料和配方根据其地区、来源和品种进行了分类。并对几种不同原料预处理技术的适用对象和条件进行了比较。还得出物理性质和生化分析，以评估固体燃料的流动性、可压性和潜在特性。为了更好地了解致密化过程中的能量消耗和转化，详细阐述了造粒装置和粘合机制。还讨论了实验室规模的单机制粒机与中试规模的工业制粒机之间的关联和差异。针对不同原料致密化情况，提出了造粒装置和工艺的优化设计建议。最后，提出了制粒工艺的操作参数因素与颗粒质量之间的关系。该综述可以为粉末压缩提供理论分析、废物转化为能源的新见解，并为实现全球碳峰值和环境战略目标提供指导。