Fundamental Processes of Solid and Liquid Biofuels Combustion

固体和液体生物燃料的基本过程燃烧木材和其他固体和液体生物质燃料作为“碳中性”能源具有吸引力。它们的有效利用需要对其燃烧过程有透彻的了解，本提案涉及生物燃料燃烧某些方面的计算工具的开发及其实验验证。所有项目的共同点是需要处理一些复杂的固体和液体混合物。固体生物质燃料通常在填充床中燃烧或气化：在炉排上有相当大的燃料颗粒的非流化床。这是一个复杂的过程，迄今为止还没有像许多燃烧过程那样被很好地理解。实用的燃料通常是各种不同颗粒大小和形状的混合物，并且通常含有几种具有不同燃烧特性的成分（例如木材废料）。提出的工作将开发在填充床燃烧数值模型中处理这种混合物的方法，并将对一系列燃料进行实验以验证该模型。诸如木屑之类的燃料颗粒也会在床上重叠，从而大大减少可用于燃烧的表面积。将开发通过在床上进行压力损失试验来测量这种影响的方法。纤维取向（晶粒）对燃烧和热解的影响也将被研究。大多数液体生物燃料，像传统的石油燃料一样，是大量成分的混合物，可以有效地建模为连续混合物，将它们表示为一个或多个概率密度函数，而不是以离散物种的形式。该提案将进一步发展连续热力学技术，以模拟液体生物燃料的蒸发和燃烧。特别感兴趣的两个领域是描述复杂混合物的化学反应动力学的方法，以便模拟点火和燃烧，以及极性化合物（如许多生物燃料中发现的醇）的非理想相平衡处理。

Fundamental Processes of Solid and Liquid Biofuels Combustion Wood and other biomass fuels, both solid and liquid, are attractive as "carbon-neutral" energy resources. Their efficient utilisation requires a thorough understanding of their processes of combustion, and this proposal addresses the development of computational tools for some aspects of biofuels combustion and their experimental verification. Common to all the projects is the need to deal with mixtures, both solid and liquid, of some complexity. Solid biomass fuels are most often burned or gasified in a packed bed: a non-fluidized bed of fairly large fuel particles on a grate. This is a complex process that as yet is not as well understood as many combustion processes. Practical fuels are usually mixtures with a wide range of different particle sizes and shapes, and often have several components with different combustion characteristics as well (e.g. wood wastes). The work proposed will develop methods for dealing with such mixtures in a numerical model of packed bed combustion, and will conduct experiments on a range of fuels to verify the model. Particles of fuels such as wood chips can also overlap in the bed, reducing the surface area available for combustion significantly. Methods will be developed to measure this effect through pressure loss tests on the bed. The effects of fibre orientation (grain) on combustion and pyrolysis will also be investigated. Most liquid biofuels, like conventional petroleum fuels, are mixtures with large numbers of components, and may be modelled effectively as continuous mixtures, representing them as one or more probability density functions rather than in terms of discrete species. This proposal will further develop continuous thermodynamics techniques for modelling the evaporation and combustion of liquid biofuels. The two areas of particular interest are methods are needed to describe chemical reaction kinetics of complex mixtures in order to model ignition and combustion, and the treatment of non-ideal phase equilibrium for polar compounds such as alcohols found in many biofuels.