Reducing NOx Emissions in High Temperature Furnaces

Ongoing collaboration between the authors' companies continues to develop applications of the dilute gas injection technique known by North American Mfg. Co. as LNI (Low NOx Injection), and by Tokyo Gas Co., Ltd. as FDI (Fuel Direct Injection). Recent developments have extended commercial applications of the technique from regenerative to ambient air, recuperative, and oxygen burners. Various strategies for orientation and packaging of oxidant and fuel nozzles are compared. The technique has been researched and applied to gas and oil-fired ambient air, oxygen, recuperative, and regenerative burners. It has been proven to significantly inhibit NOx emissions without penalties in fuel efficiency or heating capability. Examples of applications in forge furnaces, steel ladle preheating, and aluminum melting are cited