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Experimental investigation on the flame front resistance of gas channel growth with melt formation in iron ore sinter beds
Proceedings of the Combustion Institute ( IF 3.4 ) Pub Date : 2018-09-26 , DOI: 10.1016/j.proci.2018.09.027
Hao Zhou , Mingxi Zhou , Pengnan Ma , Ming Cheng

The resistance of the flame front within the solid bed constitutes a fundamental and crucial area in porous bed combustion as the flame front propagation is highly related to the productivity and product quality. This paper focuses on the iron ore sintering, a thermal agglomeration process in steel mills. The results from a detailed experimental study of the pilot-scale pot tests under the conditions of a wide range of fuel rate are presented. The primary objective is to provide better understanding of the growth of gas channels relating to melt formation in the flame front and its resistance to flow. The sintering bed was divided into several zones based on the temperature profile and component distribution. Even though there is a continuous one-to-one replacement of humidified zone with porous sintered zone, a constant air flow rate during sintering could be obtained, indicating the ∼100 mm high-temperature zone has a controlling effect on sintering bed permeability. The specific pressure drop value in high-temperature zone increases from ∼3 kPa in upper bed to ∼7 kPa in bottom bed, which varies with the bed temperature and structure properties. Both the green bed and sintered bed were scanned by X-ray computed tomography, the reconstruction and image analysis showed that the sintered bed has large gas channels and many more closed pores due to solid-melt-gas coalescence. More melt is generated when the heat is accumulated along the bed or input higher coke content, showing a propensity to suppress the gas channel growth and amplify the mismatch of gas transportation along the bed. Higher coke rate leads to a higher resistance in flame front, resulting in a slower flame front speed. These results are aimed to provide quantitative validation for improvements of a numerical sintering model in a future work.



中文翻译:

铁矿烧结矿床气体通道生长与熔体形成的火焰前沿阻力实验研究

固体床内火焰锋的阻力构成了多孔床燃烧的基本和关键领域,因为火焰锋的传播与生产率和产品质量高度相关。本文的重点是铁矿石烧结,这是钢厂的热团聚过程。给出了在各种燃油费率条件下进行中试规模罐试验的详细实验研究结果。主要目的是更好地了解与火焰前沿中的熔体形成有关的气体通道的增长及其流动阻力。根据温度分布和成分分布,将烧结床分为几个区域。即使用多孔的烧结区连续一对一地替换加湿区,在烧结过程中可获得恒定的空气流速,这表明〜100 mm的高温区对烧结床的渗透性具有控制作用。高温区的比压降值从上层床的〜3 kPa增加到下层床的〜7 kPa,随床温和结构特性的变化而变化。X射线计算机断层摄影术扫描生料床和烧结床,重建和图像分析表明,由于固溶气的聚结,烧结床具有较大的气体通道和更多的闭孔。当热量沿床层积聚或输入更高的焦炭含量时,会产生更多的熔体,这显示出有可能抑制气体通道的增长并加剧沿床层的气体传输失配。较高的焦炭率会导致较高的火焰前阻力,导致火焰前移速度变慢。这些结果旨在提供定量验证,以在将来的工作中改进数字烧结模型。

更新日期:2018-09-26
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