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Show This has been attributed to a reduction in the amount of NOx generated by the prompt NOx mechanism for these mixtures. Based on the initial tests results, it appears that the reduction in prompt NOx formation for these ultra low NOx burners becomes significant when the hydrocarbon concentration of a typical refinery fuel gas falls below 30% to 40%, i.e. greater than 60 to 70 mole % hydrogen. Tests run with varying hydrocarbon content in fuel gas mixtures of constant adiabatic flame temperature show a significant dependence of NOx on hydrocarbon content. There appears to be a nearly threefold increase in NOx emissions as the hydrocarbon content of the fuel is increased from 0% to 120/0 by volume. NOx emissions for the hydrocarbon-free mixture were nearly one-fourth that of the hydrocarbon-only fuel. The data suggests that prompt NOx may account for about 750/0 of the NOx emitted from these ultra low NOx burners. REFERENCES 1. Waibel, R. T.: Ultra Low NOx Burners for Industrial Process Heaters, Second International Conference on Combustion Technologies for a Clean Environment, Lisbon (1993) 2. Waibel, R. T., and Napier, S.: New, Low NOx Burner Design for High Temperature Process Furnaces, American Flame , ~esearch Committee/Japanese. Flame Research Committee Pacific Rim International Symposium on ' Environmental Control of Combustion Processes, Maui (1994) 3. Modi, K. and Waibel, R. T.: NOx Emissions from Process Heaters and Boilers, National Petroleum Refiners Association Environmental Conference, San Francisco (1995) 4. Miller, J. A. and Bowman, C. T.: Prog. Energy Combustion Science, Vol. 15, pp. 287 -338 (1989) 15 |