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首页> 外文期刊>Fuel >Visualization and characterization of thermo-physical behaviour of wood during devolatilization in a hot fluidized bed using X-ray radiography technique
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Visualization and characterization of thermo-physical behaviour of wood during devolatilization in a hot fluidized bed using X-ray radiography technique

机译：使用X射线射线照相技术在热流化床中脱挥发分期间木材的热物理行为的可视化和表征

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摘要

Digital X-ray Radiography (DXR), a non-destructive technique (NDT) is used to visualize and characterize the dynamics of the thermo-physical behaviour of wood during devolatilization in a hot Bubbling Fluidized Bed (BFB). X-ray radiographs of cube shaped Casuarina Equisetifolia wood of size ranging from 10 to 25 mm is used to visualize, interpret and quantify the thermal behaviour in terms of location and propagation of char front, intra-particle conversion, "true" char formation time (CFT), and physical behaviour in terms of temporal and terminal shrinkage (transverse, longitudinal and volumetric). Also, initiation and orientation of sub-surface fissure in a devolatilizing particle, leading to fragmentation is identified and qualitatively discussed. A three dimensional (3-D) mathematical model has been used to predict the progress of intra-particle conversion and the predictions are compared with the experimental data obtained from DXR.It is found that the "true" CFT inferred from DXR technique is 12% and 26% lower than that obtained by the Flame Extinction Time (FET) technique for a 10 and 15 mm particle, respectively. The terminal mean longitudinal, transverse and volumetric shrinkage are found to be in the range of 12-17%, 22-23% and 44-47%, respectively for all the particle sizes studied. The terminal volumetric shrinkage falls well within the range of 40-65% reported in the published literature. In contrast to the popular assumption in the devolatilization models, the variation of shrinkage with conversion is found to be non-linear in along-the-grain direction. From the present study it is verified/established experimentally (visually) for the first time the difference in rate of propagation of char front across and along the grain direction of the wood particle. The predictions of the 3-D model on progress of conversion compare well with the experimental findings of DXR technique. This technique can also be applied to other solid fuels.
机译：数字X射线放射照相（DXR）是一种无损技术（NDT），用于在热鼓泡流化床（BFB）脱挥发分过程中可视化和表征木材的热物理行为。尺寸为10至25 mm的方型木麻黄木料的X射线射线照相用于可视化，解释和量化热行为，包括炭前沿的位置和传播，颗粒内转化，“真实”炭形成时间（CFT），以及根据时间和末梢收缩（横向，纵向和体积）的身体行为。而且，鉴定并定性讨论了脱挥发分颗粒中亚表面裂缝的引发和取向，从而导致破裂。使用三维（3-D）数学模型预测粒子内转换的过程，并将该预测与从DXR获得的实验数据进行比较。发现从DXR技术推断出的“真实” CFT为12分别比10毫米和15毫米粒子的消光时间（FET）技术所获得的数值低％和26％。对于所有研究的粒径，最终的平均纵向，横向和体积收缩率分别为12-17％，22-23％和44-47％。最终体积收缩率很好地落在公开文献中报道的40-65％的范围内。与脱挥发分模型中流行的假设相反，收缩率随转化率的变化在沿晶粒方向上是非线性的。从本研究中，它是第一次（目视）通过实验（目视）进行了验证/确定，即炭黑在木材颗粒的颗粒方向上和沿颗粒方向的传播速率差异。 3-D模型对转换进度的预测与DXR技术的实验结果相吻合。该技术也可以应用于其他固体燃料。

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  • 来源
    《Fuel》 |2013年第10期|208-223|共16页
  • 作者

    Ruben Sudhakar Dhanarathinam; Ajit Kumar Kolar;

  • 作者单位

    Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India;

    Heat Transfer and Thermal Power Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036, India;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Wood; Radiography; Thermo-physical; Fluidized bed;

    机译：木;射线照相;热物理流化床;

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