Comparative study on the compression characteristics under mechanical and gas pressurization

Powder compression is essential in the storage and transportation processes. The compression characteristics of pulverized coal, rice husk and lignocellulose were compared under mechanical and gas pressurization respectively. The experimental results showed that the descending order of relative packing density was lignocellulose > rice husk > pulverized coal under mechanical pressurization, while an opposite trend was observed under gas pressurization. The effect of cohesion properties on compression results, such as inter-particle adhesion force and powder bed cohesion, was also investigated. For mechanical pressurization, the powder bed of cohesive biomass had higher void fraction, which was directly linked to larger relative packing density. On the contrary, gas permeated easily into the biomass powder bed, and the lower pressure drop decreased the compression capacity of gas pressurization. In addition, a model for predicting the relative packing density was proposed with an error of ± 5%.