Performance of a downdraft fixed bed gasifier employing air as the gasifying agent and eucalyptus chips in two reactor configurations

The study of gasification applied to biomass waste has emphasis due to the potential for producing energy with low environmental impact and obtaining chemical products (H2, CO, CO2, N2, light hydrocarbons such as CH4, C2H4, C2H6 and others). Efforts were concentrated on the study and optimization of a pilot downdraft gasification unit, with air as the gasifying agent and eucalyptus chips as the fuel in two configurations. The limitations of altering the temperature gradient inside the reactor and the benefit of volumetric expansion inside the reactor for the gas were observed. From 0.6 kg of chips in the optimized condition, 1.25 m3/h of synthesis gas volume was produced, with a biomass consumption rate (BCR) of 2.4 kg/h, a gas production rate (GPR) of 0,76 Nm3/ Kg, and an average production of 0.8 g/Nm3 per run. The performance of the gasifier produced at an equivalence ratio (Ф) of 0.28 a lower heating value (LHV) of the gas of 3.19 MJ/Nm3, carbon conversion efficiency (CCE) of 68.09% and cold gas efficiency (ECG) of 14.68% to obtain 11% H2, 59.26% N2, 11.64% CO, 1.50% CH4 and 16.60% CO2.