Discrete Element Modeling of the Impact Breakage of a Wet Flexible Fiber Agglomerate

Biofuels are a source of clean and renewable energy. Understanding the impact breakage of a wet fiber agglomerate is key in the design process of a biomass reactor, leading to a reduction in material processing cost. In the biomass refinement process, long biomass fibers and their agglomerates must be broken down into a slurry for subsequent mixing and chemical reaction. The most common method for the comminution of biomass fibers is using a hammer mill. Discrete element method (DEM) simulations are performed to model the breakage of biomass fibers in a hammermill by simulating a wet fiber agglomerate impacting against a target wall. A whole spectrum of impact velocities is employed in which the agglomerate remains unbroken at a low velocity and breaks into small pieces at a high velocity. Parametric studies show that the extent of breakage of the agglomerate is increased by decreasing the liquid surface tension, liquid to solid volume ratio, contact angle, and/or liquid viscosity.