OP-II-3

OP-III-B-16leaving the first area (drying - pyrolysis) to enter the zone of oxidation, also enters theair; combustible gases react with available oxygen from the air in and out asproducts: char, tar e a mix of gases (CO, CO 2 , H 2 , CH 4 , H 2 O and N 2 ) includingnitrogen from the air, considered inert and water vapor [2-3]. In the bottom of thereactor is the reduction zone, also known as gasification zone. Entering this zoneproducts of oxidation zone and react with them according to four simultaneousreactions, resulting in a greater concentration of combustible gases. Here thenitrogen and tar are considered inert. The gaseous products of this area are(CO, CO 2 , H 2 , CH 4 , H 2 O and N 2 ) [2-3].The model is able to predict the profile of molar concentrations of species and thetemperature profile in the gasifier, which are useful design parameters for materialselection and sizing of reactor. The results obtained with this model are in goodagreement with data obtained with other models and experimental data fromprevious research published in the literature.References[1]. Y. Lu, L. Guo, X. Zhang, Q. Yan, Thermodynamic modeling and analysis of biomass gasificationfor hydrogen production in supercritical water, Chemical Engineering Journal, 131 (2007) 233-244.[2]. D.L. Giltrap, R. McKibbin, G.R.G. Barnes, A steady state model of gas-char reactions in adowndraft biomass gasifier, Solar Energy, 74 (2003) 85-91.[3]. D.L. Giltrap, Investigating Downdraft Gasification of Biomass, in: Institute of FundamentalSciences, Masssey University, Palmerston North, New Zealand, 2002, pp. 156.[4]. T.H. Jayah, L. Aye, R.J. Fuller, D.F. Stewart, Computer simulation of a downdraft wood gasifierfor tea drying, Biomass and Bioenergy, 25 (2003) 459-469.[5]. N. Gao, A. Li, Modeling and simulation of combined pyrolysis and reduction zone for a downdraftbiomass gasifier, Energy Conversion and Management, 49 (2008) 3483-3490.[6]. A.K. Sharma, Equilibrium modeling of global reduction reactions for a downdraft (biomass)gasifier, Energy Conversion and Management, 49 (2008) 832-842.[7]. A.K. Sharma, Equilibrium and kinetic modeling of char reduction reactions in a downdraft biomassgasifier: A comparison, Solar Energy, 82 (2008) 918-928.[8]. J.K. Ratnadhariya, S.A. Channiwala, Three zone equilibrium and kinetic free modeling of biomassgasifier - a novel approach, Renewable Energy, 34 (2009) 1050-1058.[9]. J.K. Ratnadhariya, S.A. Channiwala, Two zone equilibrium and kinetic free modeling of gasifier,in: 12th European Conference and Technical Exhibition on Biomass for Energy, Industry andClimate Protection, Amsterdam, The Netherlands, 2002, pp. 813-816.AcknowledgementsThe authors would like to thank Dr. Donna Louise Giltrap for clarifying questionsregarding his original model of the area reduction. The financial support of the scholarshipprogram of CAPES is also gratefully.212