2021 Annual Meeting
Material Attributes Impact Flow-through Pretreatment of Air-Classified Corn Stover: Experiment and Modeling
Biomass deacetylation is an important step in price-competitive industrial ethanol production. While this process usually employs batch reactors, previous studies have proposed using a fixed-bed continuous-flow reactor to increase process efficiency. Similar processes have been proved viable for woody biomass at several scales in the pulping industry. However, applying this process to herbaceous biomass is challenging due to its significantly higher compressibility which can cause flow-induced pressure drop across the solid biomass material in the reactor. To decrease the associated risks of scale-up for flow-through herbaceous biomass deacetylation, further studies are needed to analyze the effect of feedstock attributes on critical parameters including column pressure drop and permeability. In this project, eight corn stover types, air-classified uniquely by moisture level, particle size, and feedstock purity, were prewashed in a fixed-bed, lab-scale reactor and compacted at pressures ranging from 0 to 60 PSI. Pressure drop was measured for varying flow rates up to 5 liters per minute (LPM). Permeability and particle specific surface area were predicted using non-linear empirical methods based on Darcyâs Law and the Kozeny-Carman Equation for fluid flow. Fixed-bed permeability was shown to be inversely and logarithmically proportional to compaction pressure for all sample types. Samples with higher moisture levels and larger particle size had a greater overall permeability, thus demonstrating stronger resistance to instrument-induced pressure drop. Feedstock purity did not conclusively influence permeability. In future fixed-bed deacetylation studies, these preferred feedstock types should be used to minimize pressure drop in order to reduce the chance of reactor shutdown due to bed blockage.