Moisture Management for Lignocellulosic Biomass

在加拿大，森林和农业残余物形式的大量木质纤维素生物质是可再生资源，可利用各种技术转化为生物燃料。近年来，加拿大一直是木质颗粒形式的致密生物质的主要出口国，预计这一趋势将继续下去。收获后立即使用这些残留物往往是不可行的，因为它们的水分含量很高，影响到热值、储存特性、运输成本和燃料的定价。无论生物质打算以致密化或非致密化形式使用，干燥都是必要的。此外，储存含水量较高的生物质可能会产生安全和健康问题。拟议研究项目的总体目标是调查生物干燥作为替代干燥技术的技术可行性，与传统方法相比，预计将减少能源消耗。另一个主要目标是确定储存木屑颗粒的最佳条件和通风策略。长期目标是研究能够提高生物质回收行业可持续性的技术。 研究的第一阶段包括自然干燥和生物干燥的实验室规模实验。生物干燥与堆肥的活跃阶段相吻合，它可以被看作是一个“有管理的自然干燥”过程。生物降解过程中产生的热量用于将水分从材料中排出。对于城市固体废物、粪肥和生物固体（污水污泥），生物质可在两周内有效干燥。森林和农业残留物由于木质纤维素含量较高，降解速度较慢。在生物干燥试验中，将用成熟堆肥和/或不同的真菌菌株接种生物质。还将确定生物质的相关水分吸附特性。生物干燥的干物质损失和气体排放将被量化，以估计对经济和环境的影响。在第二阶段的研究中，将使用在实际气候条件下进行的中试规模试验收集的数据进行计算机模拟和验证。

In Canada, large amounts of lignocellulosic biomass in the form of forest and agricultural residues constitute renewable resources for conversion into biofuels using a variety of technologies. Canada has been a major exporter of densified biomass in the form of wood pellets in recent years, and this trend is expected to continue. The immediate use of these residues after harvest is often unfeasible due to their high moisture content which affects the calorific value, storage properties, transport costs and the pricing of the fuel. Drying is necessary whether the biomass is intended to be used in densified or non-densified form. Moreover, storage of biomass with higher moisture content could have safety and health concerns. The overarching goal of the proposed research project is to investigate the technical feasibility of biodrying as an alternative drying technique, which is expected to reduce energy consumption compared to conventional methods. Another major objective is to determine the optimal conditions and ventilation strategy for stored wood pellets. The long-term objective is to investigate technologies that can enhance the sustainability of the biomass recycling industry. Phase I of the study involves lab-scale experiments on natural drying and biodrying. Biodrying coincides with the active phase of composting and it may be seen as a "managed natural drying" process. Heat generated from the biodegradation process is used for driving the moisture off the materials. For municipal solid waste, manure and biosolids (sewage sludge), the biomass could be effectively dried within two weeks. Forest and agricultural residues have a slower degradation rate due to their higher lignocellulosic contents. The biomass will be inoculated with mature compost and/or different strains of fungi in the biodrying tests. The related moisture sorption characteristics of the biomass will also be determined. Dry matter losses and gaseous emissions from biodrying will be quantified in order to estimate the effects on the economics and the environment. Computer simulations will be performed and validated using data collected from pilot-scale tests under actual climate conditions in Phase II of the study.