Dimensionamento e modelagem de um sistema de insuflamento de ar para otimização da queima em uma fornalha de cavaco

Abstract

The use of solid biomass as fuel in industrial thermal systems has become an attractive alternative from both energy and environmental perspectives. However, the high variability of the physical and chemical properties of biomass fuels imposes significant challenges to the combustion process, making the proper design of the air supply and distribution system essential. In this context, this work aims to perform the design and modeling of an air insufflation system applied to a eucalyptus wood chip combustion furnace intended to produce 10 tons of steam per hour, seeking to optimize the combustion process and improve the overall thermal efficiency of the boiler. The adopted methodology is initially based on the elemental characterization of the fuel and on the application of the stoichiometric combustion balance, which allows the determination of the theoretical and actual air flow rates, considering an appropriate excess air for real operating conditions. Subsequently, an energy balance of the boiler is carried out to determine the required fuel mass flow rate, taking into account the lower heating value of the eucalyptus wood chips and the thermal efficiency of the equipment. Based on these results, the hydraulic design of the air insufflation system is developed, including the calculation of distributed and localized pressure losses along ducts and air distribution orifices, as well as the selection of a suitable fan for the design conditions. Additionally, a computational fluid dynamics (CFD) analysis is performed to evaluate the airflow distribution inside the furnace and to identify recirculation zones and the degree of flow uniformity. The results indicate that the designed system is capable of supplying the required air flow rate with adequate pressure, providing a more homogeneous oxidant distribution and contributing to a more efficient and stable combustion process with reduced thermal losses.