(334c) Continuous Feeding-Discharging Behavior of Milled Biomass in Wedge-Shaped Hoppers

The commercialization of bioenergy has suffered a long time from various material handling issues, manifested as the jamming and unstable flow of particulate biomass in handling equipment like hoppers and feeders. Fundamentally, these issues are caused by the poor flowability of biomass particles, which usually have a high aspect ratio, irregular shape, complicated surface texture, and high bulk compressibility. These material attributes set biomass apart from conventional granular materials (like sands) and make it chanllenging for existing numerical approaches to predict the flow of milled biomass. Recent studies have provided improved understanding of discharge flow behavior in wedge-shaped hoppers pre-filled with biomass. However, a more common situation in practical biorefineries is the continuous feeding and discharge, which has not yet been well studied. This study investigates the continuous feeding-discharging behavior of Loblolly pine chips in wedge-shaped hoppers by combining physical experiments and discrete-element method (DEM) simulations. A graphics processing unit (GPU) computing-enabled open-sourced DEM solver is developed with a bonded-sphere particle model to characterize the flow of elongated-shaped particles. Model parameters are calibrated from a series of laboratory-scale benchmark flow tests, and the DEM model is validated by comparing the predicted flow rate against pilot-scale hopper flow tests. Simulation studies are conducted to evaluate the effects of different feeding methods, feeding rates, and feeding heights on the effective discharge in hoppers with different flow patterns (i.e., mass and funnel flow), outlet sizes, and hopper wall inclinations. We will report the obtained simulation results and propose that the maximum feeding rate to ensure continuous discharge can be described as a function of a few hopper parameters and material attributes. This study promotes the scientific understanding of the dynamic feeding-discharging behavior of milled biomass and guides the feeding control to ensure continuous material flow and transport in biorefineries.