Particle and feeding characteristics of biomass powders
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Milling of biomass is a necessary key step in suspension gasification or powder combustion. Milled biomass powders are often cohesive, have low bulk density and poor flowability leading to costly problems in fuel handling. Two different milling methods with four different biomass powders have been performed to correlate between particle and feeding properties. Charcoal, Torrefied Norway spruce, Norway spruce and reed canary grass where milled (knife mill or hammer mill) with a screen size of 1 mm. The resulting powders where analyzed using both mechanical sieving and optical sieveless particle size analysis. After bulk and tapped density tests, the powders were fed through a twin screw feeder onto an analytic scale that logged the weight data on a pc. Two tests were made, one with constant screw speed and the other using a built-in function called loss in weight feeding. The hammer mill produced more homogenous powders with more fines than the knife mill. They also had lower bulk and tapped density. The feeding tests were inconclusive as two materials where easier fed when hammer milled and two when knife milled. Hammer milled materials had better initial feeding stability. Another interesting observation was that two of the materials showed good agreement with a feeding rate that could be predicted if assuming tapped density while the other two behaved more similar to what would be the case for bulk density.
Place, publisher, year, edition, pages
2013. , 19 p.
Other Environmental Engineering
IdentifiersURN: urn:nbn:se:umu:diva-72759OAI: oai:DiVA.org:umu-72759DiVA: diva2:627253
Subject / course
Master of Science Programme in Energy Engineering