1. © Influence Of Combustion Parameters On NOx Production In An Industrial Boiler Habib, MA; Elshafei, M; Dajani, M PERGAMON-ELSEVIER SCIENCE LTD, COMPUTERS FLUIDS; pp: 12-23; Vol: 37 King Fahd University of Petroleum & Minerals http://www.kfupm.edu.sa Summary NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model furnace of an industrial boiler utilizing fuel gas. The importance of this problem is mainly due to its relation to the pollutants produced by large boiler furnaces used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NO modeling equations were solved together to present temperature and NO distribution inside the radiation and convection sections of the boiler. The boiler under investigation is a 160 MW, water-tube boiler, gas fired with natural gas and having two vertically aligned burners. The simulation study provided the NO distribution in the combustion chamber and in the exhaust gas at various operating conditions of fuel to air ratio with varying either the fuel or air mass flow rate, inlet air temperature and combustion primary air swirl angle. In particular, the simulation provided more insight on the correlation between the maximum furnace temperature and furnace average temperatures and the thermal NO concentration. The results have shown that the furnace average temperature and NO concentration decrease as the excess air factor lambda increases for a given air mass flow rate. When considering a fixed value of mass flow rate of fuel, the results show that increasing lambda results in a maximum value of thermal NO concentration at the exit of the boiler at lambda = Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

2. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. © 1.2. As the combustion air temperature increases, furnace temperature increases and the thermal NO concentration increases sharply. The results also show that NO concentration at exit of the boiler exhibits a minimum value at around swirl angle of 45 degrees. (C) 2007 Elsevier Ltd. All rights reserved. References: *FLUENT INC, 2003, FLUENT 6 1 US GUID ATTYA AM, 1990, MULTI PHASE TRANSPOR BAUBILIS DC, 1992, 5 INT C EXHIBITION P, P297 BOYD RK, 1985, 3 AUSTR C HEAT MASS, P51 CHONG AZS, 2001, IEE P-SCI MEAS TECH, V148, P95 CHUNGEN Y, 2002, FUEL, V81, P997 COELHO PJ, 1995, COMBUST SCI TECHNOL, V108, P363 COELHO PJ, 1996, J ENG GAS TURB POWER, V118, P887 DONG W, 2000, THESIS DEP MAT SCI E FOSTER T, 1994, J I ENERGY, V67, P101 FRASSOLDATI A, 2005, CHEM ENG SCI, V11, P2851 HABIB MA, 1982, NUMER HEAT TRANSFER, V5, P145 HABIB MA, 1992, ENERGY, V17, P283 HABIB MA, 2004, J HEAT MASS TRANSFER, V2 HANDBY VI, 1997, INT J HEAT VENTIL AI, V3, P101 HANSON RK, 1984, COMBUSTION CHEM, P361 KOKKINOS A, 2000, ASME INT JOINT POW G KOKKINOS A, 2001, US EPA DOE EPRI COMB LI N, 1996, UKACC INT C CONTR EX, P1016 LIU F, 1998, INT J HEAT MASS TRAN, V41, P3357 LIU X, 2001, P CSEE, V21, P80 MAGNUSSEN BF, 1976, 16 S COMB MATHUR MP, 2001, 2001 AFRC JFRC IEA C MODAK AT, 1979, FIRE RES, V1, P339 PATANKAR SV, 1980, NUMERICAL HEAT TRANS RAITHBY GD, 1990, J HEAT TRANS-T ASME, V112, P415 REYNOLDS WC, 1987, 755 LECT NOTES VON K SHIH TH, 1995, COMPUT FLUIDS, V24, P227 SHUJA SZ, 1996, COMPUT FLUIDS, V25, P133 SMITH TF, 1982, J HEAT TRANS-T ASME, V104, P602 VERSTEEG HK, 1995, INTRO COMPUTATIONAL WILCOX DC, 2000, TURBULENCE MODELING YAGA M, 2000, P 2000 INT JOINT POW, P1 ZHANG L, 1988, INT J HEAT MASS TRAN, V31, P2261 ZHENG YQ, 2000, CHINESE J CHEM ENG, V8, P247 For pre-prints please write to: mahabib@kfupm.edu.sa Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

3. © Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa