Modeling and Simulation of Reduction Zone of Downdraft Biomass Gasifier: Effect of Air to Fuel Ratio

Biomass mainly in the form of wood is the oldest form of energy used by humans. Biomass generally means a relatively dry solid of natural matter that has been specifically grown or has originated as waste or residue from handling such materials. The thermochemical conversion of biomass (pyrolysis, gasification, combustion) is one of the most promising non-nuclear forms of future energy. In the present study, the model reported in literature is simulated to study the effects of pyrolysis fraction on the outlet gas concentration in a downdraft biomass gasifier. It is found that the air to fuel ratio is one of the key parameters in the reduction zone of downdraft biomass gasifier. It effects the value of pyrolysis fraction in the model, and indirectly proportional to the pyrolysis fraction. Steady state composition and temperature profiles for the reduction zone of the downdraft biomass gasifier are also predicted for various values of air to fuel ratio.