The study investigated how oxygen and fuel supply affect the generation of NOx in a lab-scale fluidized bed reactor. By evaluating different combustion conditions, the researchers identified optimal operating conditions to minimize NOx emissions. They also compared the impact of periodic fuel and air supply fluctuations on NOx generation. The study found that periodic changes in coal and air supply led to variations in combustion gas composition, affecting NOx emissions. Overall, the research provides important insights into how NOx emissions are influenced by combustion load variations, contributing to understanding flexible operation in coal-fired power plants.