ECT Image Analysis Methods for Shear Zone Measurements during Silo Discharging Process

The paper covers the electrical capacitance tomography (ECT) data analysis on shear zones formed during silo discharging process. This is due to the ECT aptitude for detection of slight changes of material concentration. On the basis of ECT visualisations, wall-adjacent shear zone profiles are analysed for different wall roughness parameters. The analysis on changes of material concentration, based on ECT images, enables the calculation for the characteristic parameters of shear zones—size and material concentration inside the shear zone in a dynamic process of silo discharging. In order to verify the methodology a series of experiments on gravitational flow of bulk solids under various conditions were conducted with different initial granular material packing densities and silo wall roughness. The investigation shows that the increase in container wall roughness is an effective method for reducing the dynamic effects during the material discharging, since these effects are resulted from the resonance between hopper construction and trembling material. Such effects will damage industrial equipment in practical applications and need further investigation.