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Thermodynamics of wood gasification - adiabatic gasification with air at atmospheric pressure

Thermodynamik der Holzvergasung - Adiabate Luftvergasung bei Umgebungsdruck
 
: Schulzke, Tim; Unger, Christoph

Acosta, M.J.:
Advances in Energy Research. Vol.6
New York: Nova Science Publishers, 2011
ISBN: 978-1-61122-725-3
ISBN: 978-1-61122-075-9
20 pp.
English
Book Article
Fraunhofer UMSICHT Oberhausen ()
biomass gasification; wood; Equilibrium; cold gas

Abstract
Thermodynamic equilibrium calculations for gasification of wood offer the possibility to predict gasifier performance with a sufficient reliability though neglecting chemical reaction kinetics. These calculations for adiabatic gasification of wood with air were performed in HSC Chemistry near atmospheric pressure and over a broad range of equivalence ratios. Over this range, adiabatic flame temperature and cold gas efficiency show a characteristic progress, whereas both graphs have a significant inflection point or maximum at the carbon boundary point, at which solid carbon just disappears from the system. Here, it indicates the optimum operating point for an ideal gasifier, where theoretical maximum efficiencies of 85 % - 90 % can be achieved. Increased water content of the wood generally involves lower adiabatic flame temperatures due to water evaporation, but approximately the same cold gas efficiencies. In comparison, an increased air inlet temperature by using sensible heat from the produced synthesis gas instead of external heat input yields higher adiabatic flame temperatures and in the vicinity of the solid carbon boundary also higher cold gas efficiencies. For wood with higher water content drying with the sensible heat from the gasifier output is an option for increasing efficiency near the solid carbon boundary remarkably.

: http://publica.fraunhofer.de/documents/N-192339.html