Solid particle size characterization by a high-frequency collision response in pneumatic particulate flow

A novel triaxial vibration method is developed for the real-time characterization of the solid particle size distribution (PSD) in pneumatic particulate flow, which is critical for chemical industry. In this work, the particle‒wall collision and friction behaviours were analysed by the time-domain statistical and time-frequency joint methods to narrow the high-frequency response range by the initial experiment of free fall for a single particle, interparticle, and multiple particles. Subsequently, verification experiments of PSD characterization in pneumatic flow were performed. First, the quantitative triaxial energy response model that considers the particle size, shape, and mass factors were established. Second, a good agreement of the particle number identification was found between the triaxial vibration energy and mean particle size of 150–550 μm. Moreover, the performance with the best accuracy was focused on a range of 42–43 kHz in the x-axis and z-axis and 36.8–38.8 kHz in the y-axis. Finally, the individual particle energy was inversely analysed by the triaxial vibration response within the optimized frequency bands, and the PSD was characterized in real-time by a low error rate, that is, 5.2% from the XZ-axis direction of sand (42–43 kHz) and 5.6% from the XYZ-axis of glass (30.9–33.9 kHz, 46.2–47.2 kHz, 38.3–41.3 kHz for each axis response). Therefore, this research complements the existing approaches for PSD characterization in particulate multiphase flow.

本研究开发了一种新型三轴振动方法，用于气动颗粒流中固体颗粒粒径分布（Particle Size Distribution，PSD）的实时表征，该方法对化工行业至关重要。本研究通过时域统计与时频联合分析方法，对颗粒-壁面碰撞与摩擦特性展开分析；并通过单颗粒、颗粒间及多颗粒自由下落的初始实验，缩小高频响应的有效范围。随后，开展了气动流场中PSD表征的验证实验。首先，建立了兼顾颗粒粒径、形状与质量因素的定量三轴能量响应模型。其次，三轴振动能量与150–550 μm区间的平均颗粒粒径在颗粒数量识别上呈现良好的一致性。此外，识别精度最优的频段为：x轴与z轴对应42–43 kHz，y轴对应36.8–38.8 kHz。最后，通过优化频段内的三轴振动响应对单颗粒能量进行反演分析，并以低误差率实现了PSD的实时表征：砂样在XZ轴方向（42–43 kHz）的识别误差为5.2%，玻璃样在XYZ轴方向（各轴响应分别对应30.9–33.9 kHz、46.2–47.2 kHz、38.3–41.3 kHz）的识别误差为5.6%。综上，本研究填补了多相颗粒流中PSD表征现有方法的不足。