Journal of Energy Engineering (에너지공학)

The Korean Society for Energy (한국에너지학회)
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Comparative Study of Char Burn-Out and NOx Emissions in O2/N2 and O2/CO2 environments

순산소 분위기에서 촤 연소 및 질소산화물 배기특성 비교

  • Lee, Chun-Sung (Graduate School of Mechanical Engineering, Pusan National University) ;
  • Kim, Seong-Gon (Graduate School of Mechanical Engineering, Pusan National University) ;
  • Lee, Byoung-Hwa (Graduate School of Mechanical Engineering, Pusan National University) ;
  • Chang, Young-June (School of Mechanical Engineering, Pusan National University) ;
  • Jeon, Chung-Hwan (School of Mechanical Engineering, Pusan National University) ;
  • Song, Ju-Hun (School of Mechanical Engineering, Pusan National University)
  • 이천성 (부산대학교 기계공학부 대학원) ;
  • 김성곤 (부산대학교 기계공학부 대학원) ;
  • 이병화 (부산대학교 기계공학부 대학원) ;
  • 장영준 (부산대학교 기계공학부) ;
  • 전충환 (부산대학교 기계공학부) ;
  • 송주헌 (부산대학교 기계공학부)
  • Received : 2010.08.02
  • Accepted : 2011.07.28
  • Published : 2011.09.30
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Abstract

The char burn-out and NOx emissions from sub-bituminous coal were investigated in drop tube furnace under $O_2/N_2$ and $O_2/CO_2$ environments with different $O_2$ concentrations of 12, 21 and 31%. Results show that the char burn-out rate is faster as $O_2$ concentration increases higher and char burn-out rate under $O_2/CO_2$ decreases due to the lower oxygen diffusion into coal surface through the $CO_2$ rich boundary layer. NO concentration increases with increasing $O_2$ concentration, but declines at $O_2$ concentration of 31%. Meanwhile, NO emission indexes decreases monotonically with increasing $O_2$ concentration, which indicates that more NO reduction occurs with higher $O_2$ concentration probably due to greater HCN formation. For all conditions of $O_2$ concentration, the NO concentration under $O_2/N_2$ maintains higher than those of $O_2/CO_2$ due to presence of thermal NO.

본 연구에서는 Drop Tube Furnace(DTF)를 이용한 $O_2/N_2$, $O_2/CO_2$ 조건에서 산소 농도(12, 21, 31%)에 따른 아역청탄 입자의 연소특성 및 질소산화물 배출특성에 관한 실험과 수치해석을 수행하였다. $O_2/N_2$, $O_2/CO_2$ 조건에서 산소 농도가 증가함에 따라 촤 연소율이 증가하였고 $O_2/CO_2$ 조건하에서 이산화탄소 경계층에서 석탄입자 표면으로의 산소 확산계수가 낮아지기 때문에 촤 연소율이 감소하였다. 산소 농도가 증가함에 따라 배출되는 NO의 농도는 증가하지만 완전 연소 조건인 31%의 산소 농도에서는 오히려 NO의 농도가 감소하였다. 반면, NO 배출 지수는 산소가 증가함에 따라 점차 감소하였다. $O_2/CO_2$ 조건에서 NO의 농도는 Thermal NO의 결여로 인해 $O_2/N_2$ 조건보다 작게 나타났다.

Keywords

References

  1. Q. Li, C. Zhao, X. Chen, W. Wu, B. Lin, "Properties of char particles obtained under $O_{2}/N_{2}$ and $O_{2}/CO_{2}$ combustion environments," Chemical engineering and processing, 2010, 80, 1851-1855.
  2. P.A. Bejarano, Y.A. Levendis, "Single-coal-particle combustion in $O_{2}/N_{2}$ and $O_{2}/CO_{2}$ environments," Combustion and flame, 2008, 153, 270-287. https://doi.org/10.1016/j.combustflame.2007.10.022
  3. Y.Q. Hu. N. Kobayashi, M. Hasatani, "The reduction of recycled-NOx in coal combustion with $O_{2}$/recycled flue gas under low recycling ratio," Fuel, 2001, 80, 1851-1855. https://doi.org/10.1016/S0016-2361(01)00048-5
  4. R. Sangras, el al, "Oxycombustion process in pulverized coal-fied boiler: a promising technology for $CO_{2}$ capture," The 29th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL. April, 2004.
  5. G. Scheffknecht, J. Maier, B. Dhungel, P. Monckert "Investigation of Oxy-Coal combustion in Semi-technical Test Facilities," Third International Conference on Clean Coal Technologies for our Future, Cagliari, Sardinia, Itlay, May, 2007.
  6. B. Dhungel, J. Maier, G. Scheffknecht, "Emission Behaviour during Oxy-Coal Combustion," AIchE 2007 Annual Meeting, Salt Lake City, UT, November, 2007.
  7. Buhre, B.J.P., L.K. Elliott, C.D. Sheng, R.P. Gupta, T.F. Wall, "Oxy-fuel combustion technology for coal-fired power generation," Progress in Energy and Combustion Science, 2005, 31, 283-307. https://doi.org/10.1016/j.pecs.2005.07.001
  8. Solomon PR, Fletcher TH. Twenty-fifth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, PA, 1994, 463.
  9. Genetti, D. B., An Advanced Model of Coal Devolatilization Based on Chemical Structure, M.S. Thesis, Department of Chemical Engineering, Brigham Young University, Provo, UT, 1999.
  10. Field M.A., Gill D.W., Morgan B.B., Hawksley P.G.W., "Combustion of Pulverized Coal," The British Coal Utilization Research Association, Leatherhead, England. 1967.
  11. Goetz, G. J., Nsakala, N. Y., Patel, K. L., Lao, T.C., "Combustion and Gasification Kinetics of Chars from Four Commercially Significant Coals of Varying Rank," Second Annual Conference on Coal Gasification, EPRI, Palo Alto, CA. 1982.
  12. B. F. Magnussen and B. H. Hjertager., In 16th Symp. (Int'l.) on Combustion. The Combustion Institute, 1976.
  13. Bowman C.T., 14th Symp. (Int.) on Combustion, The Combustion Institute, Pittsburgh, PA, 1973, 270.
  14. Smoot, L. D., Editor and co-author, Fundamentals of Coal Combustion for Clean and Efficient Use, Elsevier, The Netherlands, (1993) (book).
  15. De Soete, G.G., "Overall reaction rates of NO and N2 formation from fuel nitrogen," 15th Symp. (Int.) on Combustion, The Combustion Institute, 1975, 1093-1102.
  16. J.J. Murphy, C.R. Shaddix, "Combustion kinetis of coal chars in oxygen-enriched environment," Combustion and flame, 2006, 144, 710-729. https://doi.org/10.1016/j.combustflame.2005.08.039
  17. R.H. Hurt, R.E. Mitchell, Proceedings of the Combustion institute, 1992, 24, 1233-1241.
  18. F.W. Terry, "Combustion processes for carbon capture," Proceedings of the Combustion institute, 2007, 31, 31-47. https://doi.org/10.1016/j.proci.2006.08.123
  19. R.H. Perry, D.W. Green, J.O. Maloney, Perry's chemical engineerings' handbook.
  20. J. Zhu, Q. Lu, T. Niu, G. Song, Y. Na, "NO emission on pulverized coal combustion in high temperature air form circulating fluidized bed - An experimental study," Fuel Processing Technology, 2009, 90, 664-670. https://doi.org/10.1016/j.fuproc.2008.12.001
  21. Y. Hu, S. Naito, N. Kobayashi, M. Hasatani, "$CO_{2}$, NOx and $SO_{2}$ emissions from the combustion of coal with high oxygen concentration gases," Fuel, 2000, 79, 1925-1932. https://doi.org/10.1016/S0016-2361(00)00047-8
  22. J.H. Pohl, A.F. Sarofim, "Devolatilization and oxidation of coal nitrogen," Sixteenth Symposium (international) on Combustion, 1976, 491-501.
  23. P.F. Nelson, A.N. Buckley, M.D. Kelly, International 13th Symposium on Combustion, The Combustion Institute, Pittsburgh, Pennsylvania, 1970, 391-401.

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