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Show introduced from the burner, but special oxygen nozzles with 30 degree diverging angle were used to prevent the interaction of fuel and oxygen jets. Oxygen velocities were much higher. In case H the oxygen nozzles were the same as example E and fuel was injected through the flue port using a special fuel nozzle with sixteen 0.032" I.D. orifices. The lowest NO. emission was achieved with this arrangement. It is important to note that low NO. emissions were achieved in Examples C,D and E without using the very high velocity oxygen jets used in examples B, F, G and H. Since higher oxygen jet velocities require high oxygen supply pressures, it is desirable to achieve low NO. emissions without using very high oxygen velocities. The stability of combustion was good for all of the above tests and CO emissions were typically 50 to 150 ppm on a dry basis. CONCLUSIONS An ultra low NO. combustion method has been developed based on the concept of ''Dilute Oxygen Combustion." DOC provides a practical method to burn different fuels with peak flame temperatures that are only 300 to 5000F above the furnace gas temperatures in many industrial furnaces. NO. emissions of 0.01 to 0.03 Ib/10' Btu (equivalent to 7 to 21 ppm for CH4-air combustion at 2% excess O2 in flue gas on a dry basis) were achieved in a test furnace operated at 23000F with furnace nitrogen concentration ranging from 34 to 68%. The new method is applicable for both air and oxygen enriched combustion conditions. REFERENCES 1. l. E. Anderson, "Oxygen Aspirator Burner And Process For Firing A Furnace," U.S. Patent 4,378,205, March 29, 1983. 2. Anderson, l.E., "A Low NO~ Low Temperature Oxygen Fuel Burner," Paper presented at the 1986 Symposium on Industrial Combustion Technologies, Chicago, IL, April 29-30, 1986. 3. Kobayashi, H., Silver, L.S., Kwan, Y., and Chen, S.L., "NO. Emission Characteristics of Industrial Burners and Control Methods under Oxygen Enriched Combustion Conditions," Paper presented at the International Flame Research Foundation, 9th Members Conference, Noordwijkerhout, May 24-26, 1989. 4. Kobayashi, H., Tuson, G.B., and Lauwers, E.l., "NO. Emissions From Oxy-Fuel Fired Glass Melting Furnaces," Paper presented at the European Society of Glass Science & Technology Conference on Fundamentals of the Glass Manufacturing Process, Sheffield, England, September 9-11, 1991. 5. H. Kobayashi, "Segregated Zoning Combustion, U.S. Patent 5,076,779, Dec. 31, 1991. 5 |
