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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=637733
• 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”的转变需要大量的生物质作为一种全球商品进行交易。由于堆积密度低，含水率高，人们认识到，造粒等致密化过程对于远距离运输生物质以实现规模经济是必不可少的。然而，尽管体积密度增加了，但目前的木质颗粒容易受到湿度和机械力的影响，因此在运输和搬运过程中很容易解体。在高湿度条件下稳定性低对加拿大球团矿行业尤其具有挑战性，加拿大球团矿行业依赖海运将大部分球团矿出口到欧洲。拟议的发现赠款旨在从根本上了解影响生物质颗粒耐久性和强度的因素。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当量的原料。这项探索研究计划主要探索生物质的物理和组成特性对致密化、处理和后续加工的影响。这将通过采用两个主要方法来实现。第一种方法为商业颗粒开发了一层保护外层，可以在储存、运输和搬运过程中保持颗粒的完整性。第二种方法在造粒前通过催化蒸汽调节步骤来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。球团周围的保护涂层将通过使用与球团表面兼容的合适涂层溶液来开发。首先，我们建议设计一种合适的均匀厚度的涂层方法。随后，将比较等离子体刻蚀表面改性与干法和湿式外涂层剂制备保护层的效率。然后，将使用更好地定义在工业相关条件下的颗粒稳定性的“代表性方法”来评估包衣颗粒的抗湿气进入和机械应力的能力。我们最近的工作表明，在球团造粒前使用“二氧化硫催化蒸汽处理”可以显著提高球团矿的性能，同时将致密化所需的力降至最低。在拟议的计划中，我们打算调查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致密，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标准化更有效的方法，以最低的能源和化学消耗生产耐用的木质颗粒。除了优化合适的水蒸气预处理条件外，我们还将比较SO2与碱性催化剂(如Ca(OH)2、NH3和Na2SO3)的适用性。拟议的研究计划预计将以环境影响评估和“颗粒包裹”和“蒸汽调节”的技术经济分析结束。这项评估将帮助工业社区选择一种环境友好但成本效益高的涂层材料和/或工艺配置，用于在生物质球团化前进行调质。该项目将培养一名PDF、一名博士和四名本科生。