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Show M-2 REDUCING N0X EMISSIONS IN HIGH-TEMPERATURE FURNACES 1998 American-Japanese Flame Research Committees International Symposium, Maui, Hawaii B. E. Cain, T. F. Robertson, and J. N. Newby* The North American Manufacturing Company, U SA Takayoshi Kurihara and Susumu Uchida Tokyo Gas Co., Ltd., Japan ABSTRACT 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 N O x 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 N O x emissions without penalties in fuel efficiency or heating capability. Examples of applications in forge furnaces, steel ladle preheating, and aluminum melting are cited. INTRODUCTION Mandated control of pollutants from industrial combustion processes has become the norm in many industries throughout the world. One of the most difficult tasks is that of controlling N O x emissions in high temperature applications. High furnace temperatures create increased kinetic rates, strong re-radiation, and hotter gas exit temperatures. These factors in turn raise N O x emissions and reduce the available heat and efficiency of the combustion process. Heat recovery devices have already been added to many applications to boost process efficiency. If limitations on emissions of greenhouse gases as presently contemplated are enacted, they are likely to be used even more widely. High air preheat temperatures resulting from their use exacerbate N O x emissions from high temperature furnaces, potentially creating an undesirable trade-off between emission of greenhouse gases such as C 0 2 and emission of ozone precursors such as N O x . A solution that can provide both high efficiency heating and low N O x emissions simultaneously may be essential to the continued viability of high temperature industries. The Japanese government and industry continue to be at the forefront in addressing these issues. A dilute gas combustion scheme named "Fuel Direct Injection" (FDI) was developed by Tokyo Gas [Ref. 1, 2, and 3] in the late 1980's to help fill this need. North American, as exclusive licensee of this technology, and Tokyo Gas continue to develop and improve commercial products and extend the range of their applications in industry. |