Discharge Characteristics Of Geldart B Particles From Aerated Hopper

This article was conducted on the self-designed aeration hopper which used silica sand and pulverized coal (Geldart group B) as the experiment materials. The influence characteristic of hopper structure parameter (hopper half-angle and outlet diameter), gas flow rate, aeration position (position A, B, C, D were half, fourth, eighth, sixteenth cone section height above the outlet respectively), multiple aeration and moisture content of pulverized coal to discharge flow rate and stability was investigated. The adjustment property of discharge flow rate was studied simultaneously. The main results were as follows:1. Using silica sand as experimental material, the discharge flow rate was always bigger than gravity discharge rate at the single aeration; and it reached a maximum at position C. The discharge flow rate increased from1627kg-h-1to5178kg-h-1. Both the flow rate and stability of multiple aeration were better than those of single aeration. In the condition of reasonable distribution of gas, the discharge process could be quick and steady, the discharge flow rate could reach6163kg-h-1.2. Experiments of three kinds of hopper half-angle θ showed that:the flow rate of sand decreased with the increasing of half-angle, but the index parameter of the relationship between discharge flow rate and1/sinθ reduced from0.62to0.44which indicated that the decreasing trend of flow rate was slowing down with the increasing of gas flow. Experiments of three kinds of hopper outlet diameter D showed that:the discharge flow rate increased with the increasing of outlet diameter, but the index parameter of the relationship between discharge flow rate and outlet diameter reduced from2.95to2.65which indicated that the increasing trend of flow rate was slowing down with the increasing of gas flow.3. Using pulverized coal as material, when discharging at the single aeration of C or D, it would form cohesive arch which made it unstable during discharge process. When discharging at a higher single aeration of A or B, the cohesive arch could not be formed which made the process stable. When the moisture content of pulverized coal was5.3%, the fluidization effect of aeration at position B was the best. When QB was equal to2Nm3·h-1, the discharge flow rate reached the maximum; and the discharge flow rate increased from381to3592kg·h-1.4. When the moisture content of pulverized coal increased from1.4%to10.6%, the flow index (ffc) decreased from8.43to3.12. When the moisture content reached10.6%, the pulverized coal could not be discharged at gravity condition. When the QA、QB、Qc、QD were0,2,0.5,0.25Nm3·h-1respectively, as the moisture content increased from5.3%to10.6%, the discharge flow rate decreased from6487kg-h"1to2556kg·h-1.5. Using pulverized coal as material, we can realize the online adjusting of discharge flow by increasing or decreasing the gas flow rate. As for the adjusting of gas flow rate, changing gas flow rate of higher position could achieve fine-tune of pulverized coal flow rate; and obvious adjustment of the discharge flow rate was easier to operate by changing lower position gas flow rate.