Tool Wear Analysis and Mitigation for Various Biomass Comminution Systems

Feedstock size reduction is essential for efficient biomass conversion. However, a comminution system inevitably experiences tool wear issues especially in processing dirty feedstocks. DOE’s Feedstock Conversion Interface Consortium (FCIC) uses integrated efforts of characterization, modeling, and testing to gain fundamental understanding of the wear mechanisms of biomass preprocessing equipment, develop analytical models to predict wear and establish material property specifications, and develop mitigations via feedstock modifications to reduce abrasiveness, cost-effective wear-resistant tool materials, and improved tool designs. Specifically, two conventional size reduction systems, hammer mill and knife mill, and the recently developed Crumbler® rotary shear were studied. Distinct tool wear mechanisms were identified for these three systems based on tribo-system analysis and worn component characterization. The content and composition of the biomass extrinsic and intrinsic inorganics were determined for various feedstocks and correlated to the tool wear performance. The effectiveness of several feedstock modification methods including air classification, size separation, and water washing on reducing tool wear was investigated. Candidate tool alloys, coatings, and surface treatments were selected and screened using bench-scale abrasion and/or erosion tests. Finite element analysis (FEA) was used to optimize the tool geometric design. Prototype tools were then fabricated using the top candidate materials and/or designs based on the laboratory wear testing results and FEA. The prototypes are being tested in actual comminution systems to demonstrate improved throughput and tool life. The knowledge and tools developed in this study enable rapid mitigation selection for sustainable performance and product quality during biomass preprocessing.

Research was sponsored by the Feedstock Conversion Interface Consortium (FCIC) of the Bioenergy Technologies Office, Office of Energy Efficiency and Renewable Energy, US Department of Energy (DOE).