Title:
Influence of Wood Species and Additives on the Combustion Behavior of Wood Pellets in Stoves and Boilers
Author(s):
Mack, R., Schön, C., Hartmann, H., Brunner, T., Obernberger, I., Behr, H.M.
Document(s):
Paper
Slide presentation
Abstract:
Wood pellets typically consist of sprucebut also other wood species are added during pellet production. Moreover, additives such as binders and kaolin are added in small ratios to improve fuel quality and combustion behavior.In this study eight different wood species were used for pellet production as well as three binders and one type of kaolin were added to sprucewood without bark, using two additivation levels. All wood pellet assortments were extensively analyzed regarding their physical and chemical properties and combusted in a 6 kW pellet stove and a 15 kW pellet boiler. The results confirmed a significant impact of the wood species on emissions for the pellet stove ranging between 85 (douglas fir) and 4,189 mg/Nm³ (apple wood) for CO and 23 (pine wood) and 263 mg/Nm³ (apple wood)for total particulate matter(TPM)-emission. Similar combustion behaviour was observed for the pellet boiler test but at a lower emission level. For wood species with a high molar Si/K-ratio,lower emissions but also serious slagging was observed. Binders may affect emissions when high additivation levels are used depending on the kind of binder. Kaolin reduced CO and TPMemissions as well as slag formation, when the additivation level was according to appropriate stoichiometric calculations. When kaolin is overdosed it may have negative impact on TPM emissions due to entrainment or problems caused by the higher ash content. Additionally, slagging is increased by high additivation levels of kaolin. Generally,at the current state of the art the pellet stove technology shows larger susceptibility towards variable pellet qualities compared to automatic pellet boilers.
Keywords:
combustion, emissions, additives, wood pellet, fuel characterization
Topic:
Biomass Conversion for Bioenergy
Subtopic:
Biomass and Bioliquids Combustion for Small and Medium Scale Applications
Event:
29th European Biomass Conference and Exhibition
Session:
2AO.5.2
Pages:
389 - 398
ISBN:
978-88-89407-21-9
Paper DOI:
10.5071/29thEUBCE2021-2AO.5.2
Price:
FREE
