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Modelling of a downdraft biomass gasifier with finite rate kinetics in the reduction zone
Author(s) -
Roy Prokash C.,
Datta Amitava,
Chakraborty Niladri
Publication year - 2009
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.1517
Subject(s) - wood gas generator , char , gas composition , heat of combustion , chemistry , thermodynamics , biomass (ecology) , chemical composition , moisture , range (aeronautics) , kinetic energy , analytical chemistry (journal) , environmental science , mechanics , materials science , combustion , physics , environmental chemistry , composite material , geology , organic chemistry , coal , oceanography , quantum mechanics
A model of a downdraft gasifier has been developed based on chemical equilibrium in the pyro‐oxidation zone and finite rate kinetic‐controlled chemical reactions in the reduction zone. The char reactivity factor ( C RF ) in the reduction zone, representing the number of active sites on the char and its degree of burn out, has been optimized by comparing the model predictions against the experimental results from the literature. The model predictions agree well with the temperature distribution and exit gas composition obtained from the experiments at C RF =100. A detailed parametric study has been performed at different equivalence ratios (between 2 and 3.4) and moisture content (in the range of 0–40%) in the fuel to obtain the composition of the producer gas as well as its heating value. It is observed that the heating value of the producer gas increases with the increase in the equivalence ratio and decrease in the biomass moisture content. The effect of divergence angle of the reduction zone geometry (in the range of 30–150°) on the temperature and species concentration distributions in the gasifier has been studied. An optimum divergence angle, giving the best quality of the producer gas, has been identified for a particular height of the reduction zone. Copyright © 2009 John Wiley & Sons, Ltd.