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首页> 外文会议>American Institute of Chemical Engineers National Meeting >Visual analysis of particle bouncing and its effect on pressure drop in dilute phase Pneumatic Conveying
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Visual analysis of particle bouncing and its effect on pressure drop in dilute phase Pneumatic Conveying

机译：粒子弹跳的视觉分析及其对稀液气动输送压降的影响

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During the pneumatic conveying of plastic pellets, it has been observed that materials with similar physical characteristics may develop substantial difference in pressure drop, whose cause is not fully understood. This experimental study focused on the dynamic behavior of the particles during conveying and its influence on pressure drop. The bouncing of the particles during pneumatic conveying in dilute phase was visually analyzed by means of a high speed video camera. The experiments included two different plastic pellets of similar size and density but different modulus of elasticity. The conveying trials were carried out in a 0.052 m I.D. aluminum pipe conveying system approximately 35 m long. The loading was controlled by an airflow control valve and a variable speed drive rotary valve. For each material, a series of tests were performed creating a matrix of six solids rates for five different air velocities. During the conveying trials the high speed video camera was used to record the actual particle motion in a horizontal section with fully accelerated flow. The videos showed significant difference in bouncing between the soft and the hard pellets. The soft pellets showed very random and intense bouncing with strong rotation, which affected the rebound considerably. In fact, some particles bounced even backwards. On the other side, the hard pellets showed significantly less bouncing and rotation. In addition to the high speed videos, in each test the pressure drop was measured in the horizontal and vertical directions. As expected, a significant difference in pressure drop was recorded for the same conveying settings when using the different materials. The pressure drop showed a close relation to the bouncing of the particles, being much higher for the soft pellets. It can be concluded that the increased pressure drop, developed by the soft polyethylene pellets, is in part due to the multiple times the particles must be reaccelerated during their transit through the conveying system. Additionally, the re duction in the average particle velocity increases the drag force. All of this resulted in up to 3X increase in pressure drop across the conveying line compared to the hard polyethylene pellets that showed significantly less bouncing.
机译：在塑料颗粒的气动输送过程中，已经观察到具有相似物理特性的材料可能会对压降产生显着差异，其原因尚未完全理解。该实验研究专注于输送过程中颗粒的动态行为及其对压降的影响。通过高速摄像机目视分析在稀相的气动输送过程中颗粒的弹跳。实验包括两个不同尺寸和密度的不同塑料颗粒，而是不同的弹性模量。输送试验在0.052米I.D.中进行。铝管输送系统大约35米长。装载由气流控制阀和变速驱动旋转阀控制。对于每种材料，进行一系列测试，用于产生五种不同的空气速度的六个固体速率的矩阵。在传送试验期间，高速摄像机用于记录水平部分中的实际粒子运动，具有完全加速的流动。该视频显示出柔软和硬质颗粒之间的弹跳的显着差异。柔软的颗粒显示出非常随机和强烈的弹跳，旋转强烈，这显着影响了反弹。事实上，一些粒子甚至向后弹起来。在另一边，硬质颗粒显着较小，弹跳和旋转显着。除高速视频外，在每个测试中，压降在水平和垂直方向上测量。如所预期的，当使用不同的材料时，记录相同输送设置的压降差异。压力下降显示与颗粒的弹跳有关的密切关系，对于软颗粒来说高得多。可以得出结论，由柔软的聚乙烯颗粒开发的增加的压降，部分是由于颗粒在通过输送系统的运输过程中必须重复颗粒的多次。另外，平均粒子速度的RE耗费增加了阻力。与硬聚乙烯颗粒相比，所有这一切导致传送线的压降增加到3倍，这显着减少了搅拌。

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