关键词: 细颗粒, 重力卸料, 料仓构型, 逆向压力梯度, 卸料形态, 卸料流率

Abstract: An experiment study on the gravity discharge characteristics of fine particles from a hopper was performed. The effects of particle size and hopper geometry on the gravity discharge rate were investigated respectively. High speed camera was employed to capture the discharge pattern of particles from the hopper and the periodicity of discharge pattern was discussed. The results showed that with the increase of particle sizes,both the interstitial pressure gradient and empty annulus effect had significant influences on the discharge rate. Thus,the discharge rate increased with particle size at first and then kept stable. Besides,as particle size increased,a transition from unstable and intermittent discharge to stable and continuous discharge was found in the discharge patterns of fine particles from conical and flat-bottomed hoppers. For the case of intermittent discharge,the discharge rate in conical hopper was lower than that in flat-bottomed hopper,due to a longer intermittent discharge period. On the other hand,for the case of continuous discharge,the discharge rate in conical hopper was higher than that in flat-bottomed hopper,due to the conical angle. Finally,by modifying the interstitial pressure gradient,a new model was proposed to predict the discharge rate of fine particles from conical and flat-bottomed hoppers. The predicted values of discharge rate were in good agreement with the experimental values.

Key words: fine particle, gravity discharge, hopper geometry, interstitial pressure gradient, discharge pattern, discharge rate