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Show Paper presented at the 1997 A F R C International Symposium, Ottawa, Ontario LOW NO, EXPERIENCES FIRING RESIDUAL OIL IN INDUSTRIAL BOILERS Scott A. Drennan* Vijay Mandayam Gary K. Rice COEN Company, Inc. 1510 Rollins Road Burlingame, CA 94010 (415) 697-0440 phone (415) 579-3255 fax Key Words: Industrial Combustion, Residual Oil, Boilers, Twin-Fluid Atomization, Emissions, NOx, Particulates, Spray Modifications ABSTRACT Residual oil continues to be the fuel of choice for many industrial steam users while environmental regulations allow its use. However, new emissions regulations on N O x and SOx are requiring substantial improvements in emissions performance or it will be regulated out of existence. This paper discusses the results and effectiveness of low N O x design modifications to residual oil firing industrial boilers. Industrial package boilers have specific performance criteria that impede the effectiveness of such low N O x techniques. Factors such as smaller furnaces, higher firing densities, lack of air preheat, widened operating envelope, simple controls, and variable fuel quality make the industrial package boiler a more challenging low N O x environment than a field erected or utility boiler. This paper summarizes the results of this N O x reduction program on several industrial water tube boilers, both package and field erected. The results indicate that significant N O x reduction can be obtained through spray pattern modification to produce a staged spray flame with rich and lean zones. The resulting spray flame reduces both thermal and fuel N O x production in cases where the furnace possessed sufficient volume to allow the increases in flame length and width resulting from the flame staging. These results indicate the effectiveness of N O x reduction techniques is directly linked to the size and residence time in the furnace and the quality of the fuel. Reductions in N O x of up to 2 5 % can be obtained simply through judicious use of spray staging. The greatest N O x reductions are obtained in field erected boilers with low firing densities as a result of the ability to stage the combustion. The variability in fuel characteristics such as viscosity, distillation curve, carbon residue, and ash composition limits the potential emissions reduction and mamtaining stable combustion. VAeeiL •Corresponding Author |