Abstract Fully-resolved simulations of the heating, ignition, volatile flame combustion and char conversion of single coal particles in convective gas environments are conducted and compared to experimental data (Molina and Shaddix, 2007). This work extends a previous computational study (Tufano et al., 2016) by adding a significant level of model fidelity and generality, in particular with regard to the particle interior description and heterogeneous kinetics. The model considers the elemental analysis of the given coal and interpolates its properties by linear superposition of a set of reference coals. The improved model description alleviates previously made assumptions of single-step pyrolysis, fixed volatile composition and simplified particle interior properties, and it allows for the consideration of char conversion. The results show that the burning behavior is affected by the oxygen concentration, i.e. for enhanced oxygen levels ignition occurs in a single step, whereas decreasing the oxygen content leads to a two-stage ignition process. Char conversion becomes dominant once the volatiles have been depleted, but also causes noticeable deviations of temperature, released mass, and overall particle conversion during devolatilization already, indicating an overlap of the two stages of coal conversion which are usually considered to be consecutive. The complex pyrolysis model leads to non-monotonous profiles of the combustion quantities which introduce a minor dependency of the ignition delay time τ ign on its definition. Regardless of the chosen extraction method, the simulations capture the measured values of τ ign very well.

中文翻译：

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使用详细的多步骤非均相动力学方法对煤颗粒燃烧进行完全解析模拟

摘要 对对流气体环境中单个煤颗粒的加热、点火、挥发性火焰燃烧和焦炭转化进行了全分辨率模拟，并与实验数据进行了比较（Molina 和 Shaddix，2007 年）。这项工作扩展了之前的计算研究（Tufano 等人，2016 年），增加了显着水平的模型保真度和通用性，特别是在粒子内部描述和异质动力学方面。该模型考虑给定煤的元素分析，并通过一组参考煤的线性叠加来插入其属性。改进的模型描述减轻了先前对单步热解、固定挥发性成分和简化颗粒内部特性的假设，并允许考虑炭转化。结果表明燃烧行为受氧浓度的影响，即对于提高的氧水平，点火发生在单个步骤中，而降低氧含量导致两阶段点火过程。一旦挥发物耗尽，焦炭转化就成为主导，但也会在脱挥发分过程中引起温度、释放质量和整体颗粒转化率的显着偏差，表明通常认为是连续的煤转化的两个阶段重叠。复杂的热解模型导致燃烧量的非单调分布，这引入了点火延迟时间 τ ign 对其定义的轻微依赖性。无论选择哪种提取方法，模拟都能很好地捕获 τ ign 的测量值。