Effect of Declination Angle of Vent Air on Flow Characteristics of a Scale Model of a Down-Fired Utility Boiler with Swirl Burners
Publication: Journal of Energy Engineering
Volume 139, Issue 4
Abstract
W-shaped furnaces equipped with swirl burners suffered from high carbon content in fly ash and high NOx emission. Using an IFA 300 constant-temperature anemometer system, cold air experiments on a scale model of a 300-MW of electrical output down-fired pulverized-coal utility boiler with swirl burners were performed to investigate the effect of the declination angle of vent air on flow characteristics of the furnace. When the angle of vent air was 28°, 35°, and 40°, the flow field in the furnace has good symmetry, which was beneficial to the stable combustion of the flame. As the angle of vent air increased, the mixing of downward airflow and vent air was delayed. At a vent-air angle of 45°, the flow field in the furnace was deflected. The deflected flow field would result in a flame short circuit, the local high temperature, an increase in the carbon content in fly ash, and a reduction of boiler efficiency. The angle of vent air had little effect on the mixing of downward airflow and staged air. Downward airflow began to turn upward in the region of the staged air nozzle and mixed weakly with the staged air. As the declination angle of vent air increased, the mixing of arch downward airflow and staged air was postponed, which extended the residence time of the pulverized coal under strong reducing atmosphere and was beneficial to reducing the generation of fuel NOx. Meanwhile, the dimensionless penetrating depth of downward airflow increased, which helped extend the residence time of the pulverized coal in the furnace, reduced the carbon content in fly ash, and increased the boiler efficiency. Considering the symmetry of the flow field and the dimensionless penetrating depth, the best angle for the vent air is 40°.
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Acknowledgments
This work was sponsored by the Hi-Tech Research and Development Program of China (863 program) (Contract No.: 2006AA05Z321) and supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (Grant No. 51121004).
References
Bilgili, M., and Sahin, B. (2009). “Investigation of wind energy density in the southern and southwestern region of Turkey.” J. Energy Eng., 135(1), 12–20.
Burdett, N. A. (1987). “The effects of air staging on NOx emissions from a 500 MW(e) down-fired boiler.” J. Instit. Energ., 60(444), 103–107.
Fan, J. R., Zha, X. D., and Cen, K. F. (2001). “Computerized analysis of low NOx W-shaped coal-fired furnaces.” Energy Fuels, 15(4), 776–782.
Fan, S. B., Li, Z. Q., Yang, X. H., Liu, G. K., and Chen, Z. C. (2010). “Influence of outer secondary-air vane angle on combustion characteristics and NOx emissions of a down-fired pulverized-coal 300 MWe utility boiler.” Fuel, 89(7), 1525–1533.
Fang, Q. Y., Wang, H. J., Wei, Y., Lei, L., Duan, X. L., and Zhou, H. C. (2010). “Numerical simulations of the slagging characteristics in a down-fired, pulverized-coal boiler furnace.” Fuel Process. Technol., 91(1), 88–96.
He, B. S., Chen, M. Q., Liu, S. M., Fan, L. J., Xu, J. Y., and Pan, W. P. (2005). “Measured vorticity distributions in a model of tangentially fired furnace.” Exp. Thermal Fluid Sci., 29(5), 537–554.
Hou, J. C., Tan, Z. F., Wang, J. H., and Xie, P. J. (2011). “Government policy and future projection for nuclear power in China.” J. Energ. Eng., 137(3), 151–158.
Kuang, M., Li, Z. Q., Yang, P. F., Jia, J. Z., and Zhu, Q. Y. (2011). “Staged-air ratio optimization for a new down-fired technology within a cold small-scale model of a 350 MWe utility boiler.” Energ. Fuels, 25(4), 1485–1496.
Li, Y. Q., and Zhou, H. C. (2006). “Experimental study on acoustic vector tomography of 2-D flow field in an experiment-scale furnace.” Flow Meas. Instrum., 17(2), 113–122.
Li, Z. Q., Fan, S. B., Su, W., Chen, Z. C., and Qin, Y. K. (2010a). “Influence of the outer secondary air vane angle on the flow field of a down-fired pulverized-coal 300 MWe utility boiler with swirl burner.” Energ. Fuels, 24(7), 3884–3889.
Li, Z. Q., Fan, S. B., Zhu, Q. Y., Su, W., Chen, Z. C., and Qin, Y. K. (2012). “Influence of staged-air flow on flow characteristics in a scale model of a down-fired utility boiler with swirl burners.” Fuel, 93, 160–166.
Li, Z. Q., Kuang, M., Zhu, Q. Y., Yang, P. F., Wu, Y. G., and Xu, S. T. (2010b). “Staged-air ratio optimization within a cold small-scale model for a MBEL down-fired pulverized-coal 300 MW (electrical) utility boiler.” Energ. Fuels, 24(9), 4883–4892.
Li, Z. Q., et al. (2010c). “Influence of staged-air on combustion characteristics and NOx emissions of a 300 MWe down-fired boiler with swirl burners.” Energ. Fuels, 24(1), 38–45.
Liang, X. H., Fan, W. C., Fan, J. R., and Cen, K. F. (1999). “Numerical simulation of the combustion in a W-shaped boiler furnace under different operating conditions.” Int. J. Energ. Res., 23(8), 707–717.
Lin, Z. C., Fan, W. D., Li, Y. Y., Li, Y. H., and Zhang, M. C. (2009). “Research of low NOx combustion with large-angle counter flow of a fuel-rich jet and its particle-dynamics anemometer (PDA) experiment.” Energ. Fuels, 23(2), 744–753.
Miao, C. X., Che, G., Wang, J. W., Zhang, Z. J., and Cheng, L. (2003). “Combustion optimization and debugging of 600 MW W-flame boiler.” Electric Power, 36, 16–19 (in Chinese).
Ren, F., Li, Z. Q., Chen, Z. C., Wang, J. J., and Chen, Z. C. (2009). “Influence of the down-draft secondary air on the furnace aerodynamic characteristics of a down-fired boiler.” Energ. Fuels, 23(5), 2437–2443.
Toufic, M., Daniel, G., and Nazli, C. (2011). “Renewable energy in Abu Dhabi: Opportunities and challenges.” J. Energ. Eng., 137(4), 169–176.
Zhou, Y. G., Xu, T. M., Hui, S. E., and Zhang, M. C. (2009a). “Experimental and numerical study on the flow fields in upper furnace for large scale tangentially fired boilers.” Appl. Therm. Eng., 29(4), 732–739.
Zhou, Y. G., Zhang, M. C., Xu, T. M., and Hui, S. E. (2009b). “Effect of opposing tangential primary air jets on the flue gas velocity deviation for large-scale tangentially fired boilers.” Energ. Fuels, 23(11), 5375–5382.
Information & Authors
Information
Published In
Journal of Energy Engineering
Volume 139 • Issue 4 • December 2013
Pages: 322 - 328
Copyright
© 2013 American Society of Civil Engineers.
History
Received: May 1, 2012
Accepted: Jan 15, 2013
Published online: Jan 17, 2013
Discussion open until: Jun 17, 2013
Published in print: Dec 1, 2013
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