Effect of air supply on combustion and emission characteristics of biodiesel in industrial furnace

Biodiesel combustion in industrial furnaces, which functions as an effective alternative for fossil fuel combustion, is an important energy-saving and emission reduction technology. In this research, the effects of optimizing air conditions on combustion and emission characteristics of waste oil-biodiesel in an industrial furnace were studied through numerical simulation and experiment. The results showed that both the maximum temperature in the furnace and the export concentration of nitric oxide (NO) increased initially and then decreased gradually with an increase in the atomization air volume, and the excess air coefficient exhibits the same pattern of influence on the temperature and NO concentration. Increasing the atomization air volume to 30 L/min produced a lifted flame. A high temperature and low export concentration of NO were observed when the excess air coefficient and atomization air volume were 1.1 and 40 L/min, respectively. The export concentration of NO and maximum temperature were increased with a rise in the air preheating temperature and air oxygen content; however, the growth trend gradually slowed down. The export concentration of NO was increased by more than 30 times, while the air oxygen content rose from 21 to 33%. Meanwhile, the export volume of fuel gas was reduced by 34.3%, which enhanced the heat efficiency of the furnace.