@phdthesis{Farsi:2017, author = {Farsi, A}, title = {Numerical and experimental investigations of particle stress and fracture for complex-shaped pellets}, year = {2017} }
TY - THES AB - Reactors with fixed beds of cylindrical particles have a wide application in the chemical industry. Ceramic particles are pelletized and fired to produce high porosity catalyst pellets of complex shapes. These pellets fill cylindrical reactor columns with particulate packing structures that are key to the in-service performance, but will suffer breakages, which impact on catalyst performance. The combined Finite-Discrete Element Method (FEMDEM) implemented in the Solidity code would appear to be ideally suited to capturing both the multi-body pellet interactions and pellet fracture and fragmentation. However, to put to use the Solidity code for this purpose and establish its capabilities and limitations required a substantive research programme, as reported in this PhD thesis. Laboratory experiments were performed to evaluate the elastic and fracture properties of reference ceramic samples, as required for input parameters for computer simulation and to investigate code capability to describe fracture in such high strength and porous media for which no previous such simulations had been reported. Each set of specimens was characterised by means of micro- and nano-indentations, ultrasonic and strength tests. Standard laboratory rigs are generally too compliable for capturing the deformations of stiff and tiny ceramic specimens. For this reason, a novel digital image correlation methodology was developed to obtain both strength and stiffness from three-point bending tests on alumina bars which would have been otherwise impossible.The effects of the catalyst support shapes on their final strength and fragmentation behaviour were investigated through controlled experiments and predominantly 2D plane stress simulations on single pellet shapes. Uniaxial compression tests and high-speed video recordings were employed to estimate the strength and fragment size respectively. The Solidity FEMDEM code was employed to simulate the effects of geometrical features and loading or AU - Farsi,A PY - 2017/// TI - Numerical and experimental investigations of particle stress and fracture for complex-shaped pellets ER -