Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
권호 표지
DOI QR코드

DOI QR Code

A Devolatilization Model of Woody Biomass Particle in a Fluidized Bed Reactor

유동층 반응기에서의 목질계 바이오매스 입자의 탈휘발 예측 모델

  • Kim, Kwang-Su (Department of Green Process and System Engineering, University of Science and Technology (UST)) ;
  • Leckner, Bo (Department of Energy and Environment, Chalmers University of Technology) ;
  • Lee, Jeong-Woo (Department of Green Process and System Engineering, University of Science and Technology (UST)) ;
  • Lee, Uen-Do (Department of Green Process and System Engineering, University of Science and Technology (UST)) ;
  • Choi, Young-Tai (Korea Institute of Industrial Technology)
  • 김광수 (과학기술연합대학원대학교(UST)) ;
  • ;
  • 이정우 (과학기술연합대학원대학교(UST)) ;
  • 이은도 (과학기술연합대학원대학교(UST)) ;
  • 최영태 (한국생산기술연구원)
  • Received : 2012.04.05
  • Accepted : 2012.08.04
  • Published : 2012.10.01
Download PDF
⟨ Previous Next ⟩

Abstract

Devolatilization is an important mechanism in the gasification and pyrolysis of woody biomass, and has to be accordingly considered in designing a gasifier. In order to describe the devolatilization process of wood particle, there have been proposed a number of empirical correlations based on experimental data. However, the correlations are limited to apply for various reaction conditions due to the complex nature of wood devolatilization. In this study, a simple model was developed for predicting the devolatilization of a wood particle in a fluidized bed reactor. The model considered the drying, shrinkage and heat generation of intra-particle for a spherical biomass. The influence of various parameters such as size, initial moisture content, heat transfer coefficient, kinetic model and temperature, was investigated. The devolatilization time linearly increased with increasing initial moisture content and size of a wood particle, whereas decreases with reaction temperature. There is no significant change of results when the external heat transfer coefficient is over 300 $W/m^2K$, and smaller particles are more sensitive to the outer heat transfer coefficient. Predicted results from the model show a similar tendency with the experimental data from literatures within a deviation of 10%.

목질계 바이오매스의 가스화 및 열분해 공정에서 탈휘발 과정은 매우 중요한 메커니즘 중의 하나이며, 공정 설계 시 반드시 반영되어야 한다. 바이오매스 입자의 탈휘발에 대한 많은 경험식이 존재하지만, 다양한 특성의 바이오매스를 특정 실험조건에서 도출한 경험식에 의존하기는 힘들다. 본 연구는 유동층 가스화 분위기에서의 바이오매스 단일 입자의 탈휘발 과정을 수학적 모델을 통하여 예측하였다. 모델은 다양한 형태의 입자를 구형태로 변환한 뒤, 입자 내부의 drying, shrinkage, heat generation을 고려하여 1차원으로 해석하였다. 또한 탈휘발 과정에 영향을 주는 입자의 크기, 반응온도, 초기 수분함량, 열전달 계수, 반응모델 등 다양한 변수에 대한 변화를 관찰하였다. 탈휘발 완료시간은 입자의 크기가 커질수록, 초기 수분함량이 높을수록 증가하였으며, 반응온도가 높을수록 선형적으로 감소하였다. 또한 외부 열전달 계수가 300 $W/m^2K$ 이상일 경우 큰 변화는 나타나지 않았지만, 입자의 크기가 작을수록 외부 열전달 계수의 영향은 크게 나타났다. 모델 예측값과 문헌의 실험값은 대체로 비슷한 경향을 나타내었으며, 오차 ${\pm}10%$ 이내로 근접하였다.

Keywords

References

  1. de Diego, L. F., Garcia-Labiano, F., Abad, A., Gayan, P. and Adanez, J., "Effect of Moisture Content on Devolatilization Times of Pine Wood Particles in a Fluidized Bed," Energy Fuels, 17, 1145-1150(2003). https://doi.org/10.1021/ef0300242
  2. Bellais, M., Modelling of the Pyrolysis of Large Wood Particles, Ph.D. thesis, KTH Royal Institue of Technology(2007).
  3. Di Blasi, C., Gonzalez-Hernandez, E. and Santoro, A., "Radiative Pyrolysis of Single Moist Wood Particles," Ind. Eng. Chem. Res., 39(4), 873-882(2000). https://doi.org/10.1021/ie990720i
  4. Di Blasi, C., "Heat, Momentum and Mass Transport through a Shrinking Biomass Particle Exposed to Thermal Radiation," Chem. Eng. Sci., 51(7), 1121-1132(1996). https://doi.org/10.1016/S0009-2509(96)80011-X
  5. Jand, N. and Foscolo, P. U., "Decomposition of Wood Particles in Fluidized Beds," Ind. Eng. Chem. Res., 44, 5079-5089(2005). https://doi.org/10.1021/ie040170a
  6. de Diego, L. F., Garcia-Labiano, F., Abad, A., Gayan, P. and Adanez, J., "Modeling of the Devolatilization of Nonspherical Wet Pine Wood Particles in Fluidized Beds," Ind. Eng. Chem. Res, 41, 3642-3650(2002). https://doi.org/10.1021/ie0201922
  7. Bryden, K. M. and Hagge, M. J., "Modeling the Combined Impact of Moisture and Char Shrinkage on the Pyrolysis of a Biomass Particle q," Fuel, 82, 1633-1644(2003). https://doi.org/10.1016/S0016-2361(03)00108-X
  8. Papadikis, K., Gu, S. and Bridgwater, A. V., "Computational Modelling of the Impact of Particle Size to the Heat Transfer Coefcient Between Biomass Particles and a Uidised Bed," Fuel Process. Technol., 91, 68-79(2010). https://doi.org/10.1016/j.fuproc.2009.08.016
  9. Kersten, S. R. A., Wang, X., Prins, W. and Swaaij, W. P. M. V., "Biomass Pyrolysis in a Fluidized Bed Reactor. Part 1: Literature Review and Model Simulations," Ind. Eng. Chem. Res., 44, 8773-8785(2005). https://doi.org/10.1021/ie0504856
  10. Semino, D. and Tognotti, L., "Modelling and Sensitivity Analysis of Pyrolysis of Biomass Particles in a Fluidized Bed," Comput. Chem. Eng., 22, 699-702(1998). https://doi.org/10.1016/S0098-1354(98)00128-8
  11. Di Felice, R., Cppola, G., Rapagna, S. and Jand, N., "Modeling of Biomass Devolatilization in a Fluidized Bed Reactor," Can. J. Chem. Eng., 77, 325-332(1999). https://doi.org/10.1002/cjce.5450770219
  12. Di Blasi, C., "Modelling the Fast Pyrolysis of Cellulosic Particles in Fluid-bed Reactors," Chem. Eng. Sci., 55, 5999-6013(2000). https://doi.org/10.1016/S0009-2509(00)00406-1
  13. Luo, Z., Wang, S. and Cen, K., "A Model of Wood Flash Pyrolysis in Fluidized Bed Reactor," Renew. Energy, 30, 377-392(2005). https://doi.org/10.1016/j.renene.2004.03.019
  14. Saastamoinen, J. J., "Simplified Model for Calculation of Devolatilization in Fluidized Beds," Fuel, 85, 2388-2395(2006). https://doi.org/10.1016/j.fuel.2006.04.019
  15. Sreekanth, M., Sudhakar, D. R., Prasad, B. V. S. S. S., Kolar, A. K. and Leckner, B., "Modelling and Experimental Investigation of Devolatilizing Wood in a Fluidized Bed Combustor," Fuel, 87, 2698-2712(2008). https://doi.org/10.1016/j.fuel.2008.02.005
  16. Sudhakar, D. R. and Kolar, A. K., "Transient Three-Dimensional Mathematical Model and Experimental Investigation of a Wet Devolatilizing Wood in a Hot Fluidized Bed," Energy Fuels, 24, 4820-4832(2010). https://doi.org/10.1021/ef100394y
  17. Gronli, M. G. and Melaaen, M. C., "Mathematical Model for Wood PyrolysissComparison of Experimental Measurements with Model Predictions," Energy Fuels, 14, 791-800(2000). https://doi.org/10.1021/ef990176q
  18. Bharadwaj, A., Baxter, L. L. and Robinson, A. L., "Effects of Intraparticle Heat and Mass Transfer on Biomass Devolatilization: Experimental Results and Model Predictions," Energy Fuels, 18, 1021-1031(2004). https://doi.org/10.1021/ef0340357
  19. Larfeldt, J., Leckner, B. and Melaaen, M. C., "Modelling and Measurements of the Pyrolysis of Large Wood Particles," Fuel, 79, 1637-1643(2000). https://doi.org/10.1016/S0016-2361(00)00007-7
  20. Babu, B.V. and Chaurasia, A. S., "Heat Transfer and Kinetics in the Pyrolysis of Shrinking Biomass Particle," Chem. Eng. Sci., 59, 1999-2012(2004). https://doi.org/10.1016/j.ces.2004.01.050
  21. Di Blasi, C., "Modeling Chemical and Physical Processes of Wood and Biomass Pyrolysis," Prog. Energy Combust. Sci., 34(1), 47-90(2008). https://doi.org/10.1016/j.pecs.2006.12.001
  22. Chan, W. R., Kelbon, M. and Krieger, B. B., "Modelling and Experimental Verification of Physical and Chemical Processes During Pyrolysis of a Large Biomass Particle," Fuel, 64, 1505-1513(1985). https://doi.org/10.1016/0016-2361(85)90364-3
  23. Thurner, F. and Mann, U., "Kinetic Investigation of Wood Pyrolysis," Ind. Eng. Chem. Process Des., 482-488(1981).
  24. Davidsson, K. O., "Biofuel Pyrolysis and On-line Alkali Measurements," Ph.D. thesis,Goteborg University(2002).
  25. Font, R., Marcilla, A., Verdu, E. and Devesa, J., "Kinetics of the Pyrolysis of Almond Shells and Almond Shells Impregnated with $CoCl_{2}$ in a Fluidized Bed Reactor and in a Pyroprobe 100," Ind. Eng. Chem. Res., 29, 1846-1855(1990). https://doi.org/10.1021/ie00105a016
  26. Gomez-Barea, A. and Leckner, B., "Modeling of Biomass Gasification in Fluidized Bed," Prog. Energy Combust. Sci., 36, 444- 509(2010). https://doi.org/10.1016/j.pecs.2009.12.002
  27. Sreekanth, M., Kumar, A. and Leckner, B., "Transient Thermal Behaviour of a Cylindrical Wood Particle During Devolatilization in a Bubbling Fluidized Bed," Fuel Process. Technol., 89, 838-850(2008). https://doi.org/10.1016/j.fuproc.2008.02.003
  28. Koufopanos, C. A., Papayannakos, N., Maschio, G. and Lucchesi, A., "Modelling of the Pyrolysis of Biomass Particles. Studies on Kinetics, Thermal and Heat Transfer Eeffects," Can. J. Chem. Eng., 69, 907-915(1991). https://doi.org/10.1002/cjce.5450690413
  29. http://en.wikipedia.org/wiki/Thermal_conductivity (Accessed: Feb. 2012).
  30. Simpson, W. and Tenwolde, A., Chapter 3. Physical Properties and Moisture Relations of Wood: Wood Handbook - Wood as an Engineering Material, University Press of the Pacific(1999).
  31. Stull, D. R., JANAF thermochemical tables, US Government Printing Office, Washington(1971).
  32. Borman, G. L. and Ragland, K. W., Combustion engineering, McGraw-Hill, New York(1998).
  33. http://www.engineeringtoolbox.com/water-vapor-d_979.html (Accessed: Feb. 2012).
  34. Siau, J. F., Transport Processes in Wood, Springer, New York (1984).
  35. Sreekanth, M., "Thermo-physical Behaviour of Wood During Devolatilization in a Fluidized Bed Combustor," Ph.D. thesis, Department of mechanical engineering, Indian Institute of Technology, Madras(2010).
  36. Palchonok, G. I., Breitholtz, C., Borodulya, V. A. and Leckner, B., in L. S. Fan and T. M. Knowlton(Ed.), Effect of turbulence on heat and mass transfer in the freeboard region of stationary and circulating fluidized beds: Fluidization IX, Engineering Foundation, New York, 413-420(1998).
  37. Konttinen, J., Kallio, S. and Kilpinen, P., Oxidation of a Single Char Particle Extention of the Model and Re-Estimation of Kinetic Rate Constants, Report, Abo Akademi, Process Chemistry Centre(2002).
  38. Molerus, O. and Mattmann, W., "Heat Transfer Mechanisms in Gas Fluidized Beds Part 1: Maximum Heat Transfer Coefficients," Chem. Eng. Technol., 15, 139-150(1992). https://doi.org/10.1002/ceat.270150302
  39. Leckner, B., in C. T. Crowe(Ed.), Chapter 5.2 Heat and mass transfer: Multiphase Flow Handbook, CRC Press(2006).
  40. Kumar, R. R. and Kolar, A. K., in A. V. Bridgwater and D. G. B. Boocock(Ed.), Effect of fuel particle shape and size on devolatilization time of Casuarina wood: Science in Thermal and Chemical Biomass Conversion Vol.2, CPL press, Newbury Berks, UK(2006).
  41. Di Blasi, C. and Branca, C., "Temperatures of Wood Particles in a Hot Sand Bed Fluidized by Nitrogen," Energy Fuels, 17, 247-254(2003). https://doi.org/10.1021/ef020146e

Cited by

  1. 3MWth급 순환유동층 바이오매스 가스화기의 운전에서 Equivalence ratio 영향 vol.34, pp.1, 2012, https://doi.org/10.12925/jkocs.2017.34.1.58