(96d) Real-Time Measurement of Volumetric Fill in a Storage Vessel and Discharge Rate By Stereoscopic 3D Optical Scanning

The volumetric degree of fill of a storage vessel can be important to operating and management requirements in the storage and handling of bulk solids. However, obtaining accurate and reliable measurements, particularly in real time, is challenging because the shape of the free surface is not usually known and is influenced by a variety of factors including discharge rate, filling conditions, and forces arising from motion and vibration. This study investigates the use of a stereoscopic 3D surface scanning method to monitor the volumetric degree of fill of agricultural materials in real-time; indicative flow rate out of the vessel is obtained from degree of fill measurements made in rapid succession. Point clouds generated from scans of the free surface of the material in a vessel, together with the 3D geometry of the vessel also obtained by 3D scanning, give a direct estimate of bulk solids volume, and hence the degree of fill. The work described in this paper was carried out with a cylindrical flat-bottomed vessel 300 mm in diameter and 700 mm high. Flow rates were controlled by circular orifices sized to give flow rates ranging from ~0.1 kg s^-1 – ~3 kg s^-1. Mass flow rate was also determined in each trial by collecting the discharge in a pail placed on platform scales and logging to a personal computer. Mass flow and volume flow rates tracked each other closely, providing encouraging support for the accord between degree of fill estimated, in static experiments, directly by scanning and indirectly from mass and bulk density.