An efficient and reliable method for determining the angle of repose of biomass by using 3D scan

This paper proposed a novel methodology to determine the angle of repose (AoR) of various biomass materials. Because of irregular shape and varying particle size distribution, slopes of biomass materials are uneven frequently and the two traditional measurement methods of AoR are therefore less applicable and reliable. In general, only partial slopes of heap surface are selected to measure AoR, although a representable slope is barely defined in standard methods. In this case, the subjective selection of slopes may result in significant deviations. Hence, we presented an efficient and reliable measurement method of AoR. In addition to the traditional bottomless cylinder test, the new technology, 3D scan, was used to digitize the generated bulk heap. Then, two data processing methods were introduced to deal with different heap forms: direct calculation based on the linear least-squares regression with regard to the whole heap surface and the pre-selection of planes for excluding outliners caused by particle bridging. For the purpose of simplifying the process, a self-developed graphic user interface (GUI) was used to analyze four kinds of biomass fuels, namely, olive stone, almond shells, forest residues and willow chips, and verify the proposed method. Both methods significantly decreased the deviations of results without increasing operating time and cost.