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Show American Flame Research Committee 1992 Fall International Symposium October 19-21. 1992 LOW-NOX IIIGH PERFORMANCE INDUSTRIAt BURNER High tenlperature industrial processes currently use highly preheated combustion air to increase thennal efficiency. However, this approach produces unacceptably high levels of NO,. With the worldwide emergence of stringent environmental requirements, industry needs a cost-effective, natural gas ftred burner that generates low levels of NO, without sacrificing process efficiency. Arthur D. Lillie, Inc. (Cambridge, MA), is leading a research program, sponsored by the Gas Research Institute, to develop a high perfonnance low NOll burner intended for high temperature gas-frred processes, such as forging, reheating, and melting of glass and aluminum. The Massachusetts Institute of Technology (MIT) and Hauck Manufacturing Company are providing scientific, engineering, and marketing support to the program. In this program, an advanced staged air recirculating (StAR) low-NO, burner has been successfully built and tested. It has demonstrated perfonnance that greatly exceeded the original program goals for NO, and CO emissions. At optimal operating conditions, the StAR burner NO, emissions were between 20 and .40 ppm (40 and 80 m~mJ~l. and CO below 50 ppm (all corrected to 3% 0 1), ~ ~ )~a y- CL' LuJtz;;::;:: The StAR burner is designed to operate on natural gas fuel and combustion air preheated up to 180(tF. Its design incorporates several NO, control combustion modifications, including: hot flue gas recirculation to reduce flame temperature and oxygen concentration in reactants; air staging to create fuel-rich, and fuel-lean combustion zones; and, reburning for the reduction of NOll in the recirculated -- ------- flue gas. r------ . Chemical kinetic and computational fluid dynamic (CfD) models were used in the development and optimization of the StAR burner design. The kinetic calculations were employed to develop infonnation on the most favorable mixtures and temperatures of air, fuel, and flue gas for minimizing the fonnation of fixed nitrogen species in the burner's fuel-rich pre-combustion chamber. CFD calculations were carried out to optimize the burner geometry and to reduce peak flame temperatures in the fuel-lean burner stage. A 2.5 million Btu/hr SIAR burner prototype was fabricated by Hauck and successfully tested at the MIT's Combustion Research Facility. The test progranl investigated over fifty burner operating conditions. Measurements were taken of NO " CO, and O2 in flue gas ex:t, and in the flame at specified furnace locations. The performance of the StAR burner was compared with the perfonnance of a state of-the-art cornmerciallow-NOIl burner of equivalent size, previously tested under identical conditions at the MIT facility. StAR burner demonstrated NO, emissions under 40 ppm, compared (0 180 ppm for the commercial burner. In the next phase of the program, an industrial field demonstration will be conducted, following a Inarket survey. It is anticipated tl at Hauck will offer the SrAR burner comlnercially in 1993. ~ \ -- |