Microwave assisted pretreatment of lignocellulosic residues for better performance as solid fuels in fluidzsed bed (FB) energy production technologies

在能源生产中开发替代燃料（木质纤维素生物质废物）具有以下优点：提高资源效率和改善废物管理，增加电力生产中的可再生能源，减少对进口能源的依赖。气化等先进的热工艺，结合木质纤维素（木质）废物的利用，可以降低能源生产部门的碳足迹。当森林或农业残留物（如谷物秸秆）作为原料或与其他燃料混合进入流化床气化炉（fbg）时，就会出现诸如灰融合和床团聚等操作问题。这是由于木质废料中的一些灰分成分（碱金属和碱土金属）与硅砂（fbg最常见的床层材料）发生不良相互作用的结果。在木材气化炉的工作温度下（50 ~ 850℃），共晶混合物产生，床团块，甚至可能导致能源生产装置关闭。为了确保以木质废料为原料的流化床锅炉的高效运行，需要对这种原料进行预处理，以去除那些有问题的元素，确保长期无干扰地运行。如何优化这类新型固体生物燃料的物理化学性质的问题可以通过将传统的预处理技术（浸出）与新的化学工程概念（微波提取）相结合来解决。在Energy Works (Hull) Ltd的支持下，这个由来自英国和欧盟的多元文化和跨学科研究人员组成的团队将开发一种新的微波预处理技术，以解决木材废料在fbg中处理或协同处理时的床团问题。提出的预处理工艺是将传统且已被证明成功的预处理方法（浸出）与新型预处理方法（微波提取）相结合而产生的。它不仅旨在优化固体生物燃料的规格，而且还旨在解决未来开发实用且经济实惠的预处理系统所面临的挑战。通过短期共同饲养和长期有效地利用木质废料，这一新工艺将使传统能源生产部门达到其可持续性标准。研究以水等离子液体对木屑的微波强化浸出工艺。这将使木质废料性能稳定，并优化FBG能源生产技术的操作行为。通过这种方式，英国被低估的生物质“废物”来源将被升级为非常理想的固体生物燃料。该新工艺的关键是将微波辐照与传统的浸出预处理相结合。水浸法对木屑中碱、碱土金属和硫元素的去除效果显著。然而，它耗时且资源密集（溶剂）。另一方面，微波提取技术已被证明可以缩短提取时间，使用更少的溶剂，甚至不需要高水分材料。因此，两种技术的结合可以改善固体生物燃料生产的废物预处理。新的预处理技术在微波机制方面仍未得到很好的理解，需要进行基础研究才能扩大规模以实现商业化。目前提议的项目将培养新一代英国领先的学术研究人员，专注于多学科解决问题的方法，并致力于培养我们未来的工程师。它还将补充最近的22个缔约方会议（COP22）马拉喀什协议，推动COP21巴黎决定的实践，通过木质废物气化等二氧化碳排放较少的技术进行大规模能源生产。

Exploitation of alternative fuels (lignocellulosic biomass waste) in energy production offers the advantages of: resource efficiency and improved waste management, increased renewables in power production and reduced dependence on imported energy. Advanced thermal processes like gasification, in combination with exploitation of lignocellulosic (woody) waste can lower the carbon footprint of the energy production sector. When forest or agricultural residues (e.g. cereal straws) are fed raw or mixed with other fuels into fluidised bed gasifiers (FBGs), operational problems like ash fusion and bed agglomeration appear. This is a result of the undesirable interactions of some of the ash constituents (alkali and alkaline earth metals) of woody waste with silica sand, which is the most common bed material of FBGs. Under the operating temperatures of wood gasifiers (> 850oC) eutectic mixtures are created, the bed agglomerates and can even cause shut down of the energy production units. To ensure efficient operation of FBGs fed on woody waste, this kind of feedstock needs to be pre-treated in order to remove those problematic elements and ensure long term operation without disturbance.The problem of how to optimise the physicochemical properties of such new types of solid biofuel can be solved by integrating traditional pre-treatment techniques (leaching) with novel chemical engineering concepts (microwave extraction).With support from Energy Works (Hull) Ltd, this multicultural and interdisciplinary team of researchers from the UK and EU, will develop a novel microwave pre-treatment technique as a solution to the bed agglomeration problem when wood waste is to be processed or co-processed in FBGs. The proposed pre-treatment process emerges from the integration of a traditional and already proven successful pre-treatment method (leaching) with a novel one (microwave extraction). It aims not only to optimize the specifications of the solid biofuel, but also to address the challenges facing future development of a practical and affordable pre-treatment system.By in short term co-feeding and in the long term by running efficiently with woody waste,this new process will allow the conventional energy production sector to meet its sustainability criteria. Development of the microwave enhanced leaching process of woody waste with ionic liquids like water is the primary target. This will enable stabilization of the woody waste properties and optimize operational behaviour in FBG energy production technologies. In this way also an underestimated biomass 'waste' source of the UK will be upgraded to a highly desirable solid biofuel.The key element of the novel process is the integration of the microwave irradiation with the traditional leaching pre-treatment of such waste. Water leaching has been proven efficient in removal of the alkali and alkaline earth metals and sulphur elements from woody waste. It is however time-consuming and resource intensive (solvents). Microwave extraction techniques on the other hand have been proven to reduce extraction time, use less solvent, or even none for high moisture materials. Thus integration of both techniques can lead to improvement in waste pre-treatment for solid biofuel production.The new pre-treatment technique is still not well understood in terms of microwave mechanisms and requires fundamental studies to allow scaling-up for commercialization. The present proposed project will develop a new generation of leading UK academic researchers focusing on a multi-disciplinary problem-solving approach and with a powerful commitment to train our future engineers accordingly.It will also complement the recent 22 Conference of Parties (COP22) Marrakesh agreement to put forward the practice of COP21 Paris decisions for large scale energy production via less CO2 emitting technologies like woody waste gasification.