High-pressure vertical pneumatic transport investigation☆
High-pressure vertical pneumatic transport investigation☆
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DOI：
10.1016/0032-5910(94)02814-1
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发表时间：
1994-05
影响因子：
5.2
通讯作者：
S. Plasynski;G. Klinzing;M. Mathur
中科院分区：
文献类型：
--
作者：
S. Plasynski;G. Klinzing;M. Mathur
在0.026米直径上对垂直气力输送进行了研究。不同压力下的白榴石管。输送气体为氮气，压力分别为101、790、2170和4238kPa.测量或目视观察并记录压降、颗粒速度、压力波动和流型。考察了不同压力下的堵塞速度、最小压降速度和颗粒摩擦因数。采用玻璃微珠(97和545μm)和煤(89和505μm)作为固体输送材料。通过将整个输送系统封装在高压安全壳中，并同时对输送管的内外进行加压，可以使用Lucite管。在所研究的所有压力下，绘制了单位长度压降与表观气速之间的Zenz型图。随着压力的增加，在给定的气速下，曲线向更高的压降方向移动。因此，最小压降时的气体速度随着压力的增加而降低。在堵塞速度上也观察到了同样的趋势。气固两相流混合物的平均颗粒速度在较高压力下比在较低压力下更容易接近表观气速。对小颗粒(89和97μm)在高压下的摩擦系数的研究表明，由于气体和固体引起的摩擦系数取决于系统的负荷。给出了小颗粒低负荷下气固两相摩擦压降的预测公式。建议将颗粒速度、堵塞速度、颗粒摩擦因数和最小压降下的速度关联式用于稀相(即ϵ>；0.9)高压输送系统的设计。
Vertical pneumatic transport was investigated in a 0.026 m i.d. Lucite tube at various pressures. Nitrogen was the conveying gas at pressures of 101, 790, 2170 and 4238 kPa. Pressure drop, particle velocity, pressure fluctuations and flow patterns were measured or visually observed and recorded. Choking velocity, velocity at minimum pressure drop and the particle friction factor were also investigated at these elevated pressures. Glass beads (97 and 545 μm) and coal (89 and 505 μm) were used as the conveyed solids. The use of Lucite tubing was made possible by encapsulating the entire transport system in a high-pressure containment vessel and pressurizing the outside and the inside of the transport tube simultaneously.A Zenz-type diagram of pressure drop per unit length versus superficial gas velocity was plotted at all pressures investigated. As pressure increased, the curve shifted toward a higher pressure drop at a given gas velocity. Gas velocity at minimum pressure drop thereby decreases as the pressure increases. The same trend is observed for the choking velocity. Average particle velocity of the gas—solid flow mixture approaches the superficial gas velocity at higher pressures more readily than it does at lower pressures.Investigation of the friction factors for the small particles (89 and 97 μm) at elevated pressures revealed that the friction factors due to the gas and solid were dependent on the loading of the system. Expressions were developed for predicting the frictional pressure drop for the gas and solid at low loadings for small particles. Correlations for particle velocity, choking velocity, particle friction factor and velocity at minimum pressure drop are recommended for designing dilute-phase (i.e. ϵ>0.9) high-pressure transport systems.