Silo emptying in aspect of the non-desctructive detection methods application

The paper presents results of concentration measurements in non-cohesive sand during free flow in rectangular and cylindrical silos using different non-invasive methods like thermography, X-ray photography, X-ray tomography and electrical capacitance tomography. The effect of the initial bulk solid density and roughness of silo walls on the concentration changes were investigated. Advantages and disadvantages of all presented methods were outlined. The possibility of application of the Electrical Capacitance Tomography (ECT) for observation the porosity changes of the bulk solid was pointed out.