(27a) Controlling Particle Size in 2 Stage Grinding Processes

Grinding raw biomass into a format suitable for conversion to a fuel, whether a dry or liquid product for thermal, chemical, or biological conversion, requires a specific particle size which is critical for the conversion pathway. Particle size also factors into the flowability of the biomass during the conversion process. Controlling the particle size of biomass through the grinding and milling process is difficult because on the inherent variability of most feedstocks. Crop type, harvest method, moisture content, age of biomass and processing method all affect the particle size of the processed biomass. Through research at the Idaho National Laboratory’s Biomass Feedstock National User Facility, several processing parameters have been identified when can be used to alter the biomass particle size during processing to meet the requirements of the conversion process. The factors tested were screen size, feed rate, mill speed, and moisture content. This research is aimed at creating a smart, dynamic control system that reacts to feedstock characteristics during processing to create a feedstock that is on spec and a control system that will ensure that is stays on spec despite the inherent variability of the feedstock.