Hopper discharge flow dynamics of milled pine and prediction of process upsets using the discrete element method

Milled pine exhibits variabilities in flow properties due to complex particle characteristics, making it challenging to ensure continuous feeding and transport in biorefineries. This work presents discrete element method (DEM) simulations of wedge-shaped hopper discharge of milled pine based on an experiment-informed DEM contact model capable of capturing the non-linearly hysteretic strain-hardening behavior of milled pine. Parametric studies of hopper discharge over varying hopper processing parameters and pine material attributes are conducted. The mass flow rate and critical arching distance predicted by DEM agree reasonably with the experiment and finite element results in the literature. Two processing parameters (opening width and semi-inclination angle) and two material attributes (rolling friction and moisture-induced cohesion) are shown to critically influence the hopper discharge dynamics. Moreover, DEM results show that the hopper with a larger inclination angle or milled pine with higher moisture content or rolling friction exhibit a higher critical arching distance.