The drying behavior of a single lignite particle (SLP) in high-temperature (600–900 °C) flue gas was investigated by experiment and numerical calculations. A self-designed horizontal fixed-bed reactor was employed for high-temperature drying experiments. Based on the drying curves obtained from these experiments, no constant-drying-rate stage was found, and the SLP drying process included stages with increasing and decreasing drying rates. To explore the drying process in depth, a mathematical model was developed in which the SLP was simplified into a simple spherical model. Based on the dry–wet zone theory, the heat- and mass-transfer equations were established to describe the drying process. The simulated results calculated using MATLAB agreed well with the experimental data. The model can predict SLP drying behaviors including the effects of the drying time, the surface and internal temperature distributions of the lignite particle, the migration of the evaporation interface inside the particle, and so on. The predicted results indicated that the migration velocity of the evaporation interface and the temperature were linearly dependent and that a temperature of 700 °C was the most suitable temperature for lignite drying. Furthermore, the drying time can be predicted using the model according to practical applications. Thus, the model can be used for the optimization of the drying process parameters and can offer guidance for the development of new drying technologies.

中文翻译：

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高温烟气中单一褐煤颗粒干燥行为的数值模拟和实验研究

通过实验和数值计算研究了单一褐煤颗粒（SLP）在高温（600–900°C）烟气中的干燥行为。自行设计的卧式固定床反应器用于高温干燥实验。根据从这些实验获得的干燥曲线，没有找到恒定的干燥速率阶段，并且SLP干燥过程包括干燥速率增加和降低的阶段。为了深入研究干燥过程，开发了一个数学模型，其中将SLP简化为简单的球形模型。基于干湿区理论，建立了传热和传质方程来描述干燥过程。使用MATLAB计算的仿真结果与实验数据吻合得很好。该模型可以预测SLP干燥行为，包括干燥时间，褐煤颗粒表面和内部温度分布的影响，颗粒内部蒸发界面的迁移等。预测结果表明，蒸发界面的迁移速度和温度呈线性关系，并且700°C是最适合褐煤干燥的温度。此外，可以根据实际应用使用该模型预测干燥时间。因此，该模型可用于优化干燥工艺参数，并可为开发新的干燥技术提供指导。蒸发界面在颗粒内部的迁移，等等。预测结果表明，蒸发界面的迁移速度和温度呈线性关系，并且700°C是最适合褐煤干燥的温度。此外，可以根据实际应用使用该模型预测干燥时间。因此，该模型可用于优化干燥工艺参数，并可为开发新的干燥技术提供指导。蒸发界面在颗粒内部的迁移，等等。预测结果表明，蒸发界面的迁移速度与温度呈线性关系，并且700°C是最适合褐煤干燥的温度。此外，可以根据实际应用使用该模型预测干燥时间。因此，该模型可用于优化干燥工艺参数，并可为开发新的干燥技术提供指导。干燥时间可以根据实际应用使用该模型进行预测。因此，该模型可用于优化干燥工艺参数，并可为开发新的干燥技术提供指导。干燥时间可以根据实际应用使用该模型进行预测。因此，该模型可用于优化干燥工艺参数，并可为开发新的干燥技术提供指导。