CFD Modeling of Reduction in NOX Emission Using HiTAC Technique

Authors: Abbas Khoshhal, Masoud Rahimi, Sayed Reza Shabanian, Ammar Abdulaziz Alsairafi

Abstract:

In the present study, the rate of NOx emission in a combustion chamber working in conventional combustion and High Temperature Air Combustion (HiTAC) system are examined using CFD modeling. The effect of peak temperature, combustion air temperature and oxygen concentration on NOx emission rate was undertaken. Results show that in a fixed oxygen concentration, increasing the preheated air temperature will increase the peak temperature and NOx emission rate. In addition, it was observed that the reduction of the oxygen concentration in the fixed preheated air temperature decreases the peak temperature and NOx emission rate. On the other hand, the results show that increase of preheated air temperature at various oxygen concentrations increases the NOx emission rate. However, the rate of increase in HiTAC conditions is quite lower than the conventional combustion. The modeling results show that the NOx emission rate in HiTAC combustion is 133% less than that of the conventional combustion.

Keywords: CFD Modeling, HiTAC, NOx, Combustion.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1078283

References:

[1] R. Tanaka and T. Hasegawa, "Innovative technology to change flame characteristics with highly preheated air combustion," in 1997 Proc. Japanese Flame Days, Osaka, Japan, pp. 129-150.
[2] A.K. Gupta, "High Temperature Air Combustion: Energy savings, Pollution reduction and Fuel reforming," in Proc. 5th Mediterranean Symposium on Combustion, the Combustion Institute, Monastir, Tunisia, 2007.
[3] S.R. Wu, W.C. Chang and J. Chiao, "Low NOx heavy fuel oil combustion with high temperature air," Fuel, vol. 86, no. 5-6, pp. 820- 828, April 2007.
[4] Q. Lu, J. Zhu, T. Niu, G. Song and Y. Na, "Pulverized coal combustion and NOx emissions in high temperature air from circulating fluidized bed," Fuel Process. Technol., vol. 89, no. 11, pp. 1186-1192, Nov. 2008.
[5] S. Li, T. Xu, S. Hui and X. Wei, "NOx emission and thermal efficiency of a 300 MWe utility boiler retrofitted by air staging," Appl. Energ., vol. 86, no. 9, pp. 1797-1803, Sep. 2009.
[6] G. L. Borman and K. W. Ragland, "Combustion Engineering," New York: McGraw-Hill, 1998, pp. 216-221.
[7] A.K. Gupta and Z. Li, "Effect of fuel property on the structure of highly preheated air flames," J. Energ. Resour-ASME, vol. 5, pp. 247-257, June 1997.
[8] T. Hasegawa, S. Mochida and A. Gupta, "Development of advanced industrial furnace using highly preheated combustion air," J. Propul. Power, vol. 18, no. 2, pp. 233-239, Aug. 2002.
[9] A. Kokkinos, D. Wasyluk, D. Adams, R. Yavorsky and M. Brower, "B&W-s experience reducing NOx emissions in tangentially-fired boilers," The US EPA/DOE/EPRI combined power plant air pollutant control symposium, the mega symposium, Chicago, Illinois, USA, August 20-23, 2001.
[10] A. Frassoldati, S. Firgerio, E. Colombo, F. Inzoli and T. Faravelli, "Determination of NOx emissions from strong swirling confined flames with an integrated CFD-based procedure," Chem. Eng. Sci., vol. 60. no. 11, pp. 2851-2869, June 2005.
[11] Fluent Inc, Fluent 6.2 User's Guide, 2005.
[12] R. Siegel and J.R. Howell, "Thermal Radiation Heat," Transfer 3rd ed. Hemisphere Publishing Corporation, Washington, 1992.
[13] B.E. Launder and D.B. Spalding, "The numerical computation of turbulent flows," Comp. Meth. Appl. Mech. Eng., vol. 3, no. 2, pp. 269- 289, March 1974.
[14] D.L. Baulch, D.D. Drysdall and D.G. Horne, "Evaluated Kinetic Data for High Temperature Reactions," Butterworth, 1973.