Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Effect of Volatile Matter and Oxygen Concentration on Tar and Soot Yield Depending on Coal Type in a Laminar Flow Reactor

LFR에서 탄종에 따른 휘발분과 산소농도가 타르와 수트의 발생률에 미치는 영향

  • Jeong, Tae Yong (Graduated School of Mechanical Engineering, Pusan Nat'l University) ;
  • Kim, Yong Gyun (Graduated School of Mechanical Engineering, Pusan Nat'l University) ;
  • Kim, Jin Ho (Graduated School of Mechanical Engineering, Pusan Nat'l University) ;
  • Lee, Byoung Hwa (Pusan Clean Coal Center, Pusan Nat'l University) ;
  • Song, Ju Hun (School of Mechanical Engineering, RIMT, Pusan Nat'l University) ;
  • Jeon, Chung Hwan (Graduated School of Mechanical Engineering, Pusan Nat'l University)
  • 정태용 (부산대학교 기계공학부) ;
  • 김용균 (부산대학교 기계공학부) ;
  • 김진호 (부산대학교 기계공학부) ;
  • 이병화 (부산대학교 화력발전에너지분석기술센터) ;
  • 송주헌 (부산대학교 기계공학부, 기계기술연구소) ;
  • 전충환 (부산대학교 기계공학부)
  • Received : 2011.12.13
  • Accepted : 2012.10.23
  • Published : 2012.12.01
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Abstract

This study was performed by using an LFR (laminar flow reactor), which can be used to carry out different types of research on coal. In this study, an LFR was used to analyze coal flames, tar and soot yields, and structures of chars for two coals depending on their volatile content. The results show that the volatile content and oxygen concentration have a significant effect on the length and width of the soot cloud and that the length and width of the cloud under combustion conditions are less than those under a pyrolysis atmosphere. At sampling heights until 50 mm, the tar and soot yields of Berau (sub-bituminous) coal, which contains a large amount of volatile matter, are less than those of Glencore A.P. (bituminous) coal because tar is oxidized by the intrinsic oxygen component of coal and by radicals such as OH-. On the other hand, at sampling heights above 50 mm, the tar and soot yields of Berau coal are higher than those of Glencore A.P. coal by reacted residual volatile matter, tar and light gas in char and flame. With above results, it is confirmed that the volatile matter content and the intrinsic oxygen component in a coal are significant parameters for length and width of the soot cloud and yields of the soot. In addition, the B.E.T. results and the images of samples (SEM) obtained from the particle separation system of the sampling probe support the above results pertaining to the yields; the results also confirm the pore development on the char surface caused by devolatilization.

본 연구에서는 다양한 석탄 연구에 적용되고 있는 층류 반응기(LFR)를 이용하여 열분해와 연소 분위기에서 탄종에 따른 화염형상을 분석하였고, 휘발분 함량이 다른 두 석탄의 타르와 수트의 발생률을 구하였으며 이를 촤 입자의 표면적 및 표면 형상 변화와 함께 비교하였다. 본 연구에서 사용된 층류 반응기는 화염형상을 가시적으로 분석하기에 뛰어나므로 석탄이 반응할 때 생성되는 수트 클라우드를 측정하여 그 형상 변화를 근거로 탈휘발의 종료 지점을 가정하였다. 휘발분 함량이 많은 Berau 탄은 Glencore A.P. 탄보다 수트 클라우드의 폭과 길이가 증가하였고, 연소 분위기에서는 촤와 수트의 산화반응에 의하여 열분해 때보다 화염과 수트 클라우드의 길이가 짧아지면서 더 밝은 빛을 내었다. 포집높이 50 mm까지에서는 휘발분 함량이 많은 Berau 탄의 타르와 수트 발생률이 Glencore A.P. 탄보다 작았다. 이는 석탄 연료의 조성 중 Berau 탄내에 상대적으로 높은 산소 성분의 함량과 OH- 같은 라디칼들로 인해 타르가 산화되기 때문이다. 반면에, 50 mm 이후부터는 Berau 탄이 Glencore A.P. 탄보다 더 많은 타르와 수트의 발생률이 나타나며 탄종간에 수트 발생률의 역전현상이 일어나는데 이는 촤 입자 내부의 휘발물질과 탈휘발 과정에서 생성된 화염 속의 잔여 타르 및 light gas 성분이 반응하여 수트를 발생시켰기 때문이다. 이를 통해서 석탄 내의 휘발분의 함량과 산소농도는 수트 클라우드의 길이와 폭에 명확한 영향을 주며, 수트 발생률에 매우 중요한 인자라는 것을 확인할 수 있었다. SEM과 B.E.T.의 결과로부터 탈휘발이 종료된 후에도 촤 입자 내부의 잔존 휘발물들이 분출되면서 타르와 수트가 발생함을 확인할 수 있었고, 각 탄의 휘발분 함량과 기공의 발달 차이를 통해서 100 mm 이후에 나타난 타르와 수트의 발생률 역전 현상을 설명할 수 있었다.

Keywords

References

  1. Korea Electric Power Coperation, "Statistics of Electric Power in Korea," 80, 20-21(2010).
  2. Solomon, P. R., Suuberg, E. M. and Serio, M. A., "Coal Pyrolysis: Experiments, Kinetic Rates and Mechanisms," Prog. Energy Combust. Sci., 18(133), 587-597(1992).
  3. Ma, J., "Soot Formation During Coal Pyrolysis," Ph.D. dissertation, Department of Chemical Engineering, Brigham Young University( 1996).
  4. Zhang, H., "Nitrogen Evolution and Soot Formation During Secondary Coal Pyrolysis," Ph.D. dissertation, Department of chemical engineering, Brigham Young University(2001).
  5. Fletcher, T. H., Ma, J., Rigby, J. R., Brown, A. L. and Webb, B. W., "Soot in Coal Combustion Systems," Prog. Energy Combust. Sci., 23(3), 283-301(1997). https://doi.org/10.1016/S0360-1285(97)00009-9
  6. Molina, A., "Evolution of Nitrogen During Char Oxidation," Ph.D. dissertation, Department of Chemical and Fuels engineering, University of Utah(2002).
  7. Essenhigh, R. H. and Howard, J. B., "Pyrolysis of Coal Particles in Pulverized Fuel Flames," I&EC Process Design and Development, 6(1), 74-84(1967). https://doi.org/10.1021/i260021a013
  8. Saastamoinen, J., Gurgel Veras, C. A., Carvalho Jr, J. A. and Aho, M., "Overlapping of The Devolatilization and Char Combustion Stages in The Burning of Coal Particles," Combust. Flame, 116(4), 567-579(1999). https://doi.org/10.1016/S0010-2180(98)00064-9
  9. Haynes, B. S., "Soot and Hydrocarbons in Combustion, In : Bartok, W. and Sarofim, A. F. (Eds)," Fossil fuel Combustion-A Source Book, John Wiley, New York, 261pp(1991).
  10. McLean, W. M., Hardesty, D. R. and Pohl, J. H., Eighteenth Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, 1239pp(1980).
  11. Brown, A. L., "Modeling Soot in Pulverized Coal Flames," Master of Science, Department of Chemical Engineering, Brigham Young University(1997).
  12. Yu, J., Lucas, J. A. and Wall, T. F., "Formation of The Structure of Chars During Devolatilization of Pulverized Coal and Its Thermoproperties: A Review," Prog. Energy Combust. Sci., 33, 135-170 (2007). https://doi.org/10.1016/j.pecs.2006.07.003
  13. Fletcher, T. H., "Chemical Structure of Char in The Transition from Devolatilization to Combustion," Energy Fuels, 6, 643-650 (1992). https://doi.org/10.1021/ef00035a016
  14. Park, C. and J. P. Appleton, "Shock-Tube Measurements of Soot Oxidation Rates," Combust. Flame, 20, 369-379(1973). https://doi.org/10.1016/0010-2180(73)90029-1
  15. Frenklach, M. and H. Wang, "Detailed Modeling of Soot Particle Nucleation and Growth," Twenty-Third Symposium (International) on Combustion, The Combustion Institute, 1559-1566(1990).
  16. Radcliffe, S. W. and J. P. Appleton, "Soot Oxidation Rates in Gas Turbine Engines," Combust. Sci. Technol., 4, 171-175(1971). https://doi.org/10.1080/00102207108952482
  17. Zeng, D., Hu, S., Sayre, A. N. and Sarv, H., "On The Rankdependence of Coal Tar Secondary Reactions," Proceedings of the Combustion Institute, 33, 1707-1714(2011). https://doi.org/10.1016/j.proci.2010.06.028
  18. Bradley, D., Lawes, M., Park, H. Y. and Usta. N., "Modeling of Laminar Pulverized Coal Flames with Speciated Devolatilization and Comparisons with Experiments," Combust. Flame, 144, 190-204(2006). https://doi.org/10.1016/j.combustflame.2005.07.007
  19. Webb, B. W., Ma, J. and Fletcher, T. H., "Conversion of Coal Tar to Soot During Ccoal Pyrolysis in A Post-flame Environment," Twenty-Sixth Symposium (International) on Combustion, The Combustion Institute, 3161-3167(1996).
  20. Saxena, S. C., "Devolatilization and Combustion Characteristics of Coal Particles," Prog. Energy Combust. Sci., 16, 55-94(1990). https://doi.org/10.1016/0360-1285(90)90025-X
  21. Solomon, P. R., Fletcher T. H. and Pugmire, R. J., "Progress in Coal Pyrolysis," Fuel, 72(5), 587-597(1993). https://doi.org/10.1016/0016-2361(93)90570-R
  22. Park, N. S., Moon, S. H., Lee, H. I., Lee, W. Y. and Rhee, H. K., "Variation in the Surface and the Gasification Properties of Coal Chars with Pyrolysis Rates," Korean Chem. Eng. Res.(HWAHAK KONGHAK), 31(2), 235-243(1993).
  23. Wang, X. and He, R., "Comparison of Fractal Properties of Porous Structures during Coal Devolatilization," Korean J. Chem. Eng., 24(3), 466-470(2007). https://doi.org/10.1007/s11814-007-0081-z

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