Exploring new ways for treating and pelletizing cellulosic biomass

探索纤维素生物质处理和造粒的新方法

• 批准号: RGPIN-2014-03802
• 负责人: Sokhansanj, Shahab
• 金额: $ 2.11万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=610653
• 关键词: Exploring; new; ways; treating; pelletizing

Transition from a “fossil fuel economy” to a “bioeconomy” requires large volumes of biomass to be traded as a global commodity. Due to low bulk density and high moisture content, densification processes such as pelletisation is recognised to be essential to transport biomass over long distances to benefit the economies of scale. However, despite an increase in the bulk density, current wood pellets are susceptible to humidity and mechanical forces, thus easily falling apart during transport and handling. Low stability at high humid conditions is challenging particularly to the Canadian pellet industry, which depends on ocean transport for exporting most of their pellets to Europe. The proposed discovery grant aims at fundamental understanding of the factors governing the durability and strength of biomass pellets. By doing so, we hope to develop effective methods to improve the pellet properties under varying environmental conditions while enabling us to use them as a feedstock for producing all different forms of fossil fuel equivalents. This Discovery Research program primarily explores the effect of physical and compositional properties of biomass on densification, handling and subsequent processing. This will be done by employing two main approaches. The first approach develops a protective outer layer for the commercial pellets that can preserve the integrity of pellets during storage, transport and handling. The second approach modifies the location and properties of cell wall polymers in biomass by a catalysed steam conditioning step prior to pelletisation with the objective of enhancing the binding characteristics of biomass particles and making pellets moisture proof. The protective coating around the pellet will be developed by using suitable coating solutions compatible with the pellet surface. At first, we propose to design a suitable method of coating with uniform thickness. Subsequently, surface modification by plasma etching will be compared with the efficiency of the protective layer produced by dry as well as wet external coating agents. The coated pellets would be then evaluated for their ability to resist moisture ingress and mechanical stress using “representative methods” which better defines the stability of the pellets at industrially relevant conditions. Our recent work has shown that the use of “SO2 catalysed steam conditioning” prior to pelletisation can substantially enhance the pellet properties while minimising the forces required for densification. In the proposed program, we intend to investigate what modifications in the cell wall polymers make the steam pretreated particles to better bind and get compacted during pelletisation and why the required energy for densification was reduced. We anticipate this fundamental knowledge would help us design and standardise more effective methods to produce durable wood pellets with minimum energy and chemical consumption. In addition to optimising the appropriate conditions of steam pretreatment, we will compare the suitability of SO2 with alkaline catalysts such as Ca(OH)2, NH3, and Na2SO3. The proposed research program is expected to conclude with an assessment of environmental impact and techno-economic analysis of both “pellet encapsulation” and “steam conditioning”. This evaluation would help the industrial community to select an environmentally benign, yet cost effective coating material and/or process configurations for conditioning biomass prior to pelletisation. The project will train one PDF, one PhD, and four undergraduate students.

从“化石燃料经济”向“生物经济”过渡需要大量生物量作为全球商品进行交易。由于低堆积密度和高水分含量，致密化过程（如造粒）被认为是长距离运输生物质以实现规模经济的关键。然而，尽管体积密度增加，但目前的木质颗粒易受湿度和机械力的影响，因此在运输和处理过程中容易破碎。高湿度条件下的低稳定性对加拿大颗粒工业来说尤其具有挑战性，该行业依赖海洋运输将大部分颗粒出口到欧洲。拟议的发现补助金旨在从根本上了解生物质颗粒的耐用性和强度的因素。通过这样做，我们希望开发有效的方法来改善颗粒在不同环境条件下的性能，同时使我们能够将它们用作生产所有不同形式的化石燃料等效物的原料。 这个发现研究计划主要探讨生物质的物理和成分特性对致密化，处理和后续加工的影响。这将通过采用两种主要方法来实现。第一种方法为商业颗粒开发一种保护外层，可以在储存、运输和处理过程中保持颗粒的完整性。第二种方法在造粒之前通过催化蒸汽调节步骤改变生物质中细胞壁聚合物的位置和性质，目的是增强生物质颗粒的结合特性并使颗粒防潮。 通过使用与颗粒表面相容的适当包衣溶液，在颗粒周围形成保护性包衣。首先，我们提出设计一个合适的方法，涂层厚度均匀。随后，将通过等离子体蚀刻进行的表面改性与通过干和湿外部涂层剂产生的保护层的效率进行比较。然后使用“代表性方法”评价包衣丸粒抵抗湿气侵入和机械应力的能力，所述方法更好地定义了丸粒在工业相关条件下的稳定性。 我们最近的研究表明，在造粒前使用“SO2催化蒸汽调节”可以大大提高颗粒性能，同时最大限度地减少致密化所需的力。在拟议的计划中，我们打算研究细胞壁聚合物中的哪些修饰使蒸汽预处理的颗粒在造粒过程中更好地结合和压实，以及为什么致密化所需的能量减少。我们预计这些基本知识将帮助我们设计和推广更有效的方法，以最低的能源和化学品消耗生产耐用的木屑颗粒。除了优化蒸汽预处理的适当条件外，我们还将比较SO2与Ca（OH）2、NH3和Na 2SO 3等碱性催化剂的适用性。 拟议的研究计划预计将结束与环境影响的评估和技术经济分析的“颗粒封装”和“蒸汽调节”。该评估将帮助工业界选择环境友好但具有成本效益的涂层材料和/或工艺配置，用于在造粒之前调节生物质。该项目将培养一名PDF，一名博士和四名本科生。