Numerical simulation of gas penetration and powder compression during high-pressure dynamic load in silo

The powder consolidation and equipment damage caused by frequent pressurization of the lock hopper silo seriously affect stable powder discharge and transportation. This paper investigated the powder compression and gas permeation characteristics during the silo pressurization by experiment and simulation. The spherical glass powder and irregularly shaped coal powder were selected as the granular materials. The modified drag model agrees well with the experiments for spatial pressure cumulative distribution and full-process pressure drop. The coal powder has a higher average compression ratio than the glass powder. The local porosity of the powder layer experiences two stages of rapid decrease and slow stabilization. The powder compression arises from particle rearrangement and bed pore structure reconstruction under airflow disturbance. The nonlinear growth of pressure accumulation curves at different spatial points in the early stage of silo pressurization forms a fusiform envelope surface. As the average pressure-increasing rate increases, the peak gas pressure gradient of the powder layer increases approximately linearly. The penetration time difference of glass powder between powder layers I and V is less than 1 s, while that of coal powder is close to 4 s. There was a significant time hysteresis effect for gas penetration in the coal powder silo.

Graphic abstract