Combustion Using Oxygen-Lancing in a Reheating Furnace

Fuel economy has been a primary issue in the steel industry because it uses large amounts of energy, such as the gaseous fuel of byproduct gas. Furthermore, reheating throughput capacity has been a key issue because it can improve furnace efficiency, leading to fuel economy. Many attempts have tried improving fuel economy using oxygen in a reheating furnace. Oxygen-lancing technology was developed to increase fuel economy and maintain the same level of NOx concentration simultaneously. Mechanisms that inject oxygen into flames locally causing flame quenching and at the same time suppressing the increase in NOx concentration due to recirculation of reheating furnace-burned gases are key to this study. Various oxygen concentrations for its lancing were used to investigate its effects on furnace temperature and NOx concentration in a test furnace. It was determined that 30% of oxygen was optimal regarding fuel economy and NOx concentrations. Oxygen was injected into the flame using two lancing pipes at 11° in a design capacity of 125 MW. The results showed a 3-5% increase in fuel economy and the same level of NOx concentration in the furnace.