An experimental and response-surface-based optimization approach towards production of producer gas in a circulating fluidized bed gasifier using blends of renewable fibre-based biomass mixtures

Biomass is a green source of power since it has minimal to no impact on biodiversity and offers global security for ecological sustainability. Gasification is a thermochemical procedure that turns a source into a by-product (fuel gas). Biomass has an edge over carbon fuels because it is sustainable. It acts as a steady source of feedstock and works as a viable candidate for energy production because it is sustainable. A few other negative repercussions of its extraordinary use include the persistent unpredictability of demand and supply for fossil fuels, environmental harm, and the consequences of climate change. Different factors, such as temperature, particle size, biomass composition, gasifier design, operating conditions, etc., have an impact on a biomass gasifier's efficiency. During gasification, a number of simultaneous reactions actually happen and some components can serve as both reactants and products. We are reporting for the first time the optimization of a biomass mixture (sugarcane bagasse and sawdust) along with the equivalence ratio and air flow rate. Preliminary experiments were conducted to ascertain the range and levels of operations of three factors, such as the equivalence ratio (ER), air flow rate, and biomass ratio. Optimization involving Box-Behnken design was utilised to decipher the effect of three influencing parameters such as the biomass mixture of sugarcane bagasse and sawdust (25%, 50%, and 75%); low air flowrates (10.5, 13.0, and 16.5 L h-1) and equivalency ratios (0.2, 0.3, and 0.4) on gas yield, tar yield, and gas heating value of biomass using an intrinsic circulating fluidized-bed reactor. All stochastic parameters validated our model. An optimal gas yield, tar yield, and gas heating value of 1.881 Nm3 kg-1, 11.360, and 8.188 were predicted at an equivalence ratio (ER) of 0.3, an air flow rate of 16.5 L h-1, and a biomass ratio of 0.75 (75% sugarcane bagasse to 25% sawdust ratio) at a desirability of 1.00. The experimental values were found to be: gas yield (1.867 Nm3 kg-1), tar yield (14.0 g Nm-3), and gas heating value (8.15 MJ Nm-3). Trials were conducted in order to warrant the predicted circumstances and the results were found to be correlated with experimental values. Effects of process parameters on the energy efficiency of biomass gasification are examined. The highest energy efficiency is observed for a blend of biomass and air as a gasifying medium.