When sizing energy crops to be packaged for use as a biomass feedstock for biofuels, bioproducts or biopower, there are several factors throughout the supply chain that should be considered. While our finished products are tailored to the application of the consumer, these guidelines ensure each production run achieves the desired quality and specification. It is essential to understand the variables and how to manage them.
- Crop package – bale size, bale type, method of harvest
- Moisture content
- Storage method and age of material
- Sizing equipment and rate of feed
- Maintenance of equipment
- Finished product specification
Whether shredding baled biomass such as switchgrass, miscanthus or stover or fine milling these and other feedstocks using conventional equipment such as a hammer mill, the moisture content greatly affects the performance of the equipment. Through experience and industry knowledge we have developed a criteria that ensures that we only accept raw material from the field that meets our standards. Improperly stored material should be rejected.
For fine milling, it is important to feed the mill at a rate appropriate to the capacity of the mill in relation to the screen size. A steady, consistent feed produces the best results where surging or overwhelming the mill can blind or damage screens. We inspect our mill screens and cutting surfaces each shift to ensure proper sizing. The abrasive nature of energy crops wears screens, hammers and knives down over time and will affect your finished particle size.
The fibrous characteristic of energy crops creates a unique challenge in sizing. The geometry of each particle size permits spearing of material through the mill screens—particles are longer than they are wide and will “dive” through the holed screen opening. Understanding this tendency and the finished product specification will allow you to select the appropriate mill set up. The proper balance of fines and elongated particles in our finished product must be achieved to maximize quality and efficiency.
Through Genera’s proprietary BIN-SPEC™ system, we can meet any customers need with preprocessed, high quality feedstocks. Combining our biomass supply chain services with our expert milling expertise provides a comprehensive solution for any biomass user.
By Clay Dye, Project Manager
