Packing Characteristics of Biomass

Berichte aus der Energietechnik
Stefan Hamel
On the Packing Properties of Fixed Beds
for Thermal Fuel Conversion
Shaker Verlag
Aachen 2010
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Zugl.: Siegen, Univ., Habil.-Schr., 2010
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ISBN 978-3-8322-9173-0
ISSN 0945-0726
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Kurzfassung
“On the Packing Properties of Fixed Beds for Thermal Fuel Conversion”
Stefan Hamel
ISBN 978-3-8322-9173-0
Packed beds of fuel wood in the form of chips or pellets are commonly found in thermal
conversion processes such as combustion or gasification. This thesis is concerned with the
characterization of spatial voidage distribution inside fuel wood chip beds, which is of great
importance for flow and reactor modelling.
On the basis of a random deposition approach, a packing model was developed in order to
transfer geometrical bed structures into CFD software for subsequent flow simulations.
In addition, an experimental investigation of voidage distribution by bed solidification,
sectioning, and subsequent image analysis of the cuts was carried out for packings of different
commercially available wood chips and pellets, in order to derive a mathematical expression
correlating radial voidage distribution.
The findings of both the experimental results and the simulations are used to interpret fixedbed wood combustion results from a laboratory-scale combustion tube and a commercial
small-scale underfeed stoker.
Keywords:
solid fuel, wood chips, pellets, particle, radial, voidage, porosity, image analysis, CFD,
simulation, random packing model, underfeed stoker, combustion, gasification
Schlagwörter:
Fester Brennstoff, Holz, Hackschnitzel, Pellets, Partikel, radial, Lückengrad, Porosität,
Bildauswertung, CFD, Simulation, Packungs-Modellierung, Unterschubfeuerung,
Verbrennung, Vergasung