长条状粗颗粒在垂直管路中最小输送速度试验研究

随着陆地金属资源的日益枯竭,深海矿产资源已经成为各国的重要战略目标。在深海采矿过程中,海底锰结核的形状除了圆球状,还有长条状等,颗粒形状对固液两相流管道输送特性具有很大影响。基于固液两相流垂直管道提升输送试验系统,探究不同工况下长条状颗粒在垂直上升流中最小输送速度的变化规律及特性,并得到了长条状群体颗粒最小输送速度计算公式。结果表明:长条状颗粒在垂直管道中上升过程中,颗粒中心轴与输送方向趋向于垂直,使颗粒在管道截面的投影面积最大化;长条状单颗粒的最小输送速度随着颗粒长径比增大而减小;在不同长径比工况下,随着管段颗粒平均浓度减小,长条状群体颗粒的最小输送速度均增大,且随着长径比增大,群最小输送速度减小。

Experimental study on minimal transporting velocity of long particles in vertical pipeline

The focus of international competition is gradually shifted to the strategic resources of sea with decreasing land resources of the countries concerned, so deep-sea mining resources have become an important strategic target. In deep sea mining, the shape of the manganese nodule is not only globular, but also long-shaped and so on. Particle shape has great influence on the pipeline transportation characteristics of solid-liquid two phase flow. Based on the solid-liquid two phase flow vertical pipeline lifting and conveying test system, the characteristics of minimal transporting velocity of long-shaped particles in vertical upward flow under different working conditions are studied. And the formula for calculating the minimal transporting velocity of group long-shaped particles is obtained. The results are concluded as follows: During the ascending process of long-shaped particles in the vertical pipeline, the central axis of particles tends to be perpendicular to the conveying direction, which maximizes the projected area of the particles in the pipeline section. The minimal transporting velocity of the single long-shaped particle decreases with the increase of the long-shaped particle''s length-diameter ratio. The minimal transporting velocity of the group long-shaped particles increases with the decrease of average volume concentration in pipe section under different length-diameter ratio conditions. With the increase of the length-diameter ratio, the minimal transporting velocity of the group long-shaped particles decreases.