TY - JOUR

T1 - A Mathematical Modeling and Validation Study of NOx Emissions in Metal Processing Systems.

AU - Malikov, G.

AU - Lisienko, V.

AU - Malikov, K. Y.

AU - Viskanta, R.

PY - 2002

Y1 - 2002

N2 - The model is based on separate calculations of prompt and thermal NOx and is accomplished using CFD code for flow, temperature and concentration fields in the combustion system. Thermal NOx is calculated with the Zeldovich model. The prompt NOx is considered to be independent of residence time and is computed with detailed kinetic data based GRI-Mech version 2.11 and CHEMKIN code by assuming that every computational cell is a perfectly stirred reactor. Three main parameters are considered to be critical in NOx production: 1) air equivalence ratio, 2) temperature, and 3) mixture dilution with combustion products. All of these parameters and methane oxidation reaction rates are readily available in every cell of the CFD domain. Once NOx emission index is computed by GRI-Mech in every cell, NOx reaction rate is easily evaluated by multiplying it with the methane oxidation reaction rate. The NOx concentration field is then calculated using known CFD transport parameters. Comparison of model predictions with measurements is made for a wide range of industrial natural gas-fired burners installed in combustion chambers and furnaces. The flame temperatures were in the range of 1400-2100 K, velocities were in the range of 10-200 m/s, burner nozzles were in the range of diameters 5-550 mm, and the combustion chamber or furnace internal equivalent size in the range of 0.05-3.5 m. Good agreement has been obtained in most cases.

AB - The model is based on separate calculations of prompt and thermal NOx and is accomplished using CFD code for flow, temperature and concentration fields in the combustion system. Thermal NOx is calculated with the Zeldovich model. The prompt NOx is considered to be independent of residence time and is computed with detailed kinetic data based GRI-Mech version 2.11 and CHEMKIN code by assuming that every computational cell is a perfectly stirred reactor. Three main parameters are considered to be critical in NOx production: 1) air equivalence ratio, 2) temperature, and 3) mixture dilution with combustion products. All of these parameters and methane oxidation reaction rates are readily available in every cell of the CFD domain. Once NOx emission index is computed by GRI-Mech in every cell, NOx reaction rate is easily evaluated by multiplying it with the methane oxidation reaction rate. The NOx concentration field is then calculated using known CFD transport parameters. Comparison of model predictions with measurements is made for a wide range of industrial natural gas-fired burners installed in combustion chambers and furnaces. The flame temperatures were in the range of 1400-2100 K, velocities were in the range of 10-200 m/s, burner nozzles were in the range of diameters 5-550 mm, and the combustion chamber or furnace internal equivalent size in the range of 0.05-3.5 m. Good agreement has been obtained in most cases.

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UR - http://www.scopus.com/inward/record.url?partnerID=8YFLogxK&scp=0036926178

U2 - 10.2355/isijinternational.42.1175

DO - 10.2355/isijinternational.42.1175

M3 - Article

VL - 42

SP - 1175

EP - 1181

JO - ISIJ International

JF - ISIJ International

SN - 0915-1559

IS - 10

ER -