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MATEMATICAL MODEL FOR DOWNDRAFT BIOMASSGASIFIER IN STEADY STATEFelipe Orlando Centeno Gonzalez 1 , Electo Eduardo Silva Lora 1 ,Rubenildo Vieira Andrade 1 , René Lesme Jaén 2OP-III-B-161 Núcleo de Excelência em Geração Térmica e Distribuída – NEST,Universidade Federal de Itajubá - (Brazil), fcenteno@ingenieros.com.2 Universidad de Oriente – (Cuba)Thermo-chemical gasification is likely to be the most cost-effective process toconvert solid fuel into gaseous fuels [1]. In this process the biomass goes into areactor under a restricted amount of oxygen below the stoichiometric, taking placewithin it a series of thermochemical processes that result in a mixture of gases. Thechemical energy contained within the gas produced depends on its composition.Then, the chemical composition determine fuel quality, high concentration ofcombustible gases such as H 2 , CH 4 and CO increase the energy of combustion ofthe gas. Among the various types of gasifiers within which can be carried outbiomass gasification is the downdraft gasifier, among other things, this ischaracterized by producing a gas with low particulate [2] allowing the use of it inequipments such as turbines, internal combustion engines, fuel cells, etc. Biomassgasification has emerged as a promising technology to meet energy needs,particularly in remote areas away from mains supply.During gasification occur four fundamental processes (drying, pyrolysis, oxidationand reduction) and each of these processes are characterized by certain physicaland chemical phenomena. In downdraft gasifiers unlike other types of reactors, it wasfound that these processes occur virtually separated into different areas of thereactor. Several researchers [2-9] take advantage of this peculiarity to divide themathematical models of downdraft gasifiers in several areas. This paper shows thedevelopment of a model of three zones: drying, pyrolysis, oxidation and reduction.The gasifier modeled is a fixed bed downdraft reactor, where biomass enters the topof the reactor, while gas enters a medium height and the gas exits through thebottom of the reactor.The upper submodel corresponds to the phenomena of drying and pyrolysistogether, in this area biomass enters the top, as the temperature increases themoisture is being released and then thermal decomposition occurs, resulting char,water vapor and a series volatile species (CO, CO 2 , H 2 , CH 4 and C 2 H 2 )[8]. Products211