Thermodynamic analysis of heat and mass

This study presents a CFD analysis of heavy fuel oil combustion in a 6.7 MW vertically-fired industrial furnace using the commercial software Fluent, aimed at enhancing combustion performance by adjusting fuel and burner parameters. The motivation stems from the necessity to improve process heat generation in the Oil refinery of the National oil company (INA) in Rijeka, Croatia. The research method involved modeling transport and reaction processes within the furnace and comparing the CFD results with existing measurement data from literature, achieving satisfactory agreement. Different parameters such as air excess ratio, fuel droplet diameter, spray cone half-angle, and burner swirl number were examined to determine their impact on the combustion process. Findings indicate that optimal performance is realized at an air excess ratio of 1.15, with medium-sized droplets (~100 μm) providing the best mixing with air, thus facilitating complete combustion while preventing excessive CO emissions. Moreover, the study found that small spray cone angles detrimentally affect air-fuel mixing, while an appropriate swirl number is crucial for maintaining efficient combustion dynamics. The results highlight the complexity of combustion modeling and the importance of parameter optimization for industrial applications.