Abstract:
The influence of carbonization on emission characteristics of rice husk briquettes in a fixed-bed reactor were investigated in this study. Rice husk briquettes were combusted in a fixed bed operated under counterflow mode of flame propagation. Emissions levels for NOx, SOx, unburnt hydrocarbons (CxHy), CO and CO2 were measured under varying biochar and air-mass flow rate conditions. Biochar in the fuel samples were varied uniformly between 25 and 100% while air mass flux was varied uniformly between 0.02 and 0.6 kg/m2.s. It was established that carbonization increases emissions of NOx, SOx, CO2 and decreases emissions of CxHy. Briquettes with high amount of carbonized rice husks emitted high amount of NOx and SOx contrary to the amount of N and S present in these fuels indicating a stronger contribution from higher combustion temperatures. On the other hand, all emissions except CO were directly proportional to air mass flux up to stoichiometric condition which was approximately at 0.31 kg/m2.s. These findings underscore the potential of carbonized rice husk briquettes as a cleaner alternative for biomass combustion.
