Aamiri Osama Bu, Thilakaratne Rajeeva, Tumuluru Jaya Shankar, Satyavolu Jagannadh
Conn Center for Renewable Energy Research, University of Louisville, Louisville, KY 40292, USA.
750 MK Simpson Boulevard, Energy Systems Laboratory, Idaho National Laboratory, Idaho Falls, ID 83415, USA.
Bioengineering (Basel). 2019 Sep 20;6(4):87. doi: 10.3390/bioengineering6040087.
Biomass-derived coal or "biocoal" produced using a torrefaction process presents a carbon-neutral option of coal for power generation. While torrefaction delivers a carbon content and hydrophobicity comparable to coal, it lowers its density and creates material handling, storage, and transportation challenges. Densification into briquettes would help mitigate these challenges. However, the torrefied biomass is difficult to densify and may require the use of binders, which are expensive and can be incompatible with respect to material and emissions. A cost-effective approach to utilize lignin in-situ of the biomass to promote binding during densification was demonstrated using a pilot-scale briquetter unit during this study. Lignin, a cross-linked polymer, tends to break down and lose its binding ability under high-temperature conditions of torrefaction. In this paper, we investigated the use of a lightly torrefied material as a binder-LTM (biomass torrefied in the transition region of non-reactive and reactive temperature ranges of torrefaction). When mixed with torrefied biomass and densified together under suitable moisture and temperature conditions, the lignin is shown to mobilize and provide binding to the briquettes. The results showed that briquettes produced using LTM as binder and 10% to 11% moisture provided in-situ binding, improved density and durability, and produced hydrophobic briquettes.
采用烘焙工艺生产的生物质衍生煤或“生物煤”是一种用于发电的碳中和煤选项。虽然烘焙后的生物煤的碳含量和疏水性与煤炭相当，但它降低了密度，并带来了材料处理、储存和运输方面的挑战。压制成型煤有助于缓解这些挑战。然而，烘焙后的生物质难以压实，可能需要使用粘合剂，而粘合剂价格昂贵，在材料和排放方面可能不相容。在本研究中，使用中试规模的压块机装置展示了一种在生物质原位利用木质素以促进压实过程中粘结的经济有效方法。木质素是一种交联聚合物，在烘焙的高温条件下容易分解并失去其粘结能力。在本文中，我们研究了使用轻度烘焙材料作为粘合剂——LTM（在烘焙的非反应性和反应性温度范围的过渡区域烘焙的生物质）。当与烘焙后的生物质混合并在合适的湿度和温度条件下一起压实时，木质素显示出能够发挥作用并为型煤提供粘结力。结果表明，使用LTM作为粘合剂且含水量为10%至11%生产的型煤具有原位粘结性，提高了密度和耐久性，并生产出了疏水型煤。
