(661b) Understanding the Effect of Particle Characteristics on Flowability of Biomass Slurries

Feeding wet biomass slurries into a high-pressure, high-temperature reactors presents significant challenge such as feed pump plugging issues. To address this, we have explored methods to improve slurry flowability and minimize plugging through adding flow aids. However, the addition of flow aids can increase the overall cost of the biomass conversion process. In this study, we investigate alternative approaches to enhance biomass particle flowability without relying on flow aids. Specifically, we examine the effects of biomass particle size distribution, the presence of small-particle-size (<1 mm) materials (byproducts of size reduction), and biomass densification. To conduct our analysis, we designed and constructed a continuous cold flow loop with a progressive cavity pump and transparent piping. The biomass slurry flow rate was 190 L per hour for the cold flow experiments, encompassing various biomass compositions including softwood, hardwood, clean softwood with 10% bark, and clean hardwood with 10% bark. The biomass solids concentrations in the slurries was increased from 1 wt% at the onset of the experiment, until pump plugging occurred. Throughout the experiments, parameters such as slurry viscosity, volume concentration of biomass solids, biomass particle porosity, particle size distribution, as well as settling and deposition velocities of biomass particles were measured. These comprehensive measurements provide valuable insights for enhancing biomass slurry flowability in industrial scale biorefineries.