volume | PIER Journals

Abstract

Microwave pyrolysis overcomes the disadvantages of conventional pyrolysis methods by efficiently improving the quality of final pyrolysis products. Biochar, one of the end products of this process is considered an efficient vector for sequestering carbon to offset atmospheric carbon dioxide. The dielectric properties of the doping agents (i.e., char and graphite) were assessed over the range of 25°-400°C and used to develop a finite element model (FEM). This model served to couple electromagnetic heating, combustion, and heat and mass transfer phenomena and evaluated the advantages of selective heating of woody biomass during microwave pyrolysis. The dielectric properties of the doping agents were a function of temperature and decreased up to 100°C and thereafter remained constant. Regression analysis indicated that char would be a better doping substance than graphite. The simulation study found that doping helped to provide a more efficient heat transfer within the biomass compared to non-doped samples. Char doping yielded better heat transfer compared to graphite doping, as it resulted in optimal temperatures for maximization of biochar production. The model was then validated through experimental trials in a custom-built microwave pyrolysis unit which confirmed that char doping would be better suited for maximization of biochar.

1. Intergovernmental Panel on Climate Change (IPCC) "IPCC fourth assessment report: Climate change 2007,", June 2013.
doi:http://www.ipcc.ch/publications and data/publications and data Google Scholar

2. Climate Change, Government of Canada "Canada's action on climate change,", June 2013.
doi:http://www.climatechange.gc.ca/default.asp?lang=En&n=72F16 A84-1 Google Scholar

3. Environment Canada "National inventory report 1990--2011: Greenhouse gas sources and sinks in Canada --- Executive summary,", June 2013.
doi:http://www.ec.gc.ca/gesghg/default.asp?lang=En&n=68EE206C-1&ofse Google Scholar

4. Agriculture and Agri Food Canada (AAFC) "Agriculture residue,", June 2008.
doi:http://www4.agr.gc.ca/AAFC-AAC/display-a±cher.do?id=122651040602 Google Scholar

5. Statistics Canada "Human activity and the environment: Annual statistics," Catalogue No. 16-201-X, 2009, June 2013.
doi:http://www.statcan.gc.ca/pub/16-201-x/16-201-x2009000-eng.pdf Google Scholar

6. Wu, H. and H. Abdullah, "Biochar as a fuel: 1. Properties andgrindability of biochars produced from the pyrolysis of Mallee wood under slow-heating conditions," Energy & Fuels, Vol. 23, No. 8, 4174-4181, 2009.
doi:DOI: 10.1021/ef900494t Google Scholar

7. Lehmann, J., "Bio-energy in the black," Frontiers in Ecology and the Environment, Vol. 5, No. 7, 381-387, 2007.
doi:10.1890060133 Google Scholar

8. Joseph, S., C. Peacocke, J. Lehmann, and P. Munroe, "Developing a biochar classification and test methods," Biochar for Environmental Management, Science and Technology, 107-126, 2009.
doi:10.1080/02773813.2011.607535 Google Scholar

9. Kleiner, K., "The bright prospect of biochar," Nature Reports Climate Change, Vol. 3, 2009.
doi:DOI:10.1038/climate.2009.48 Google Scholar

10. International Biochar Initiative (IBI) "Biochar is a valuable soil additive,", 2010, June 2013.
doi:http://www.biochar-international.org/biochar Google Scholar

11. Brownsort, P. A., "Biomass pyrolysis processes: Performance parameters and their influence on biochar system benefits," M.Sc. thesis, School of Geosciences, University of Edinburgh, 2009, June 2013.
doi:http://hdl.handle.net/1842/3116 Google Scholar

12. Dutta, B., G. S. V. Raghavan, and M. Ngadi, "Surface characterization and classification of slow and fast pyrolysed biochar using novel methods of pycnometry and hyper-spectral imaging," Journal of Wood Chemistry and Technology, Vol. 32, No. 2, 105-120, 2011.
doi:DOI: 10.1080/02773813.2011.607535 Google Scholar

13. Copson, D. A., Microwave Heating, 2nd Ed., xi-615, Avi Pub. Co., Westport, Conn., 1975.
doi:10.1016/S0165-2370(98)00079-5

14. Metaxas, A. C., Foundations of Electroheat. A Unified Approach, 400, John Wiley & Sons, 1996.

15. Thostenson, E. T. and T. W. Chow, "Microwave processing: Fundamentals and applications," Composites: Part A, Vol. 30, 1055-1071, 1999.
doi:10.2529/PIERS090320171147 Google Scholar

16. Babu, B. V. and A. S. Chaurasia, "Pyrolysis of biomass: Improved models for simultaneous kinetics and transport of heat, mass and momentum," Energy Conversion and Management, Vol. 45, No. 9--10, 1297-1327, 2004.
doi:DOI: 10.1016/j.enconman.2003.09.013 Google Scholar

17. Blasi, D., "Comparison of semi-global mechanisms for primary pyrolysis of lignocellulosic fuels," Journal of Analytical and Applied Pyrolysis, Vol. 47, No. 1, 43-64, 2008.
doi:DOI: 10.1016/S0165-2370(98)00079-5 Google Scholar

18. Dutta, B., S. R. S. Dev, Y. Gariepy, and G. S. V. Raghavan, "Finite element modelling of microwave pyrolysis of biomass," Proceedings of 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT), July 2010.
doi:10.1021/ie901336k Google Scholar

19. Dev, S. R. S., Y. Gariepy, and G. S. V. Raghavan, "Measurement of dielectric properties and finite element simulation of microwave pretreatment for convective drying of grapes," PIERS Online, Vol. 5, No. 7, 690-690, 2009. Google Scholar

20. Delisle, G. Y., K. L. Wu, and J. Litva, "Couples finite element and boundary element method in electromagnetics," Comp. Phys. Commun., Vol. 68, No. 1--3, 255-278, 1991.
doi:DOI: 10.1016/0010-4655(91)90203-W Google Scholar

21. Dev, S. R. S., Y. Gariepy, V. Orsat, and G. S. V. Raghavan, "FDTD modeling and simulation of microwave heating of in-shell eggs," Progress In Electromagnetics Research M, Vol. 13, 229-243, 2010. Google Scholar

22. Sanga, E. C. M., "Microwave assisted drying of composite materials: Modelling and experimental validation," Dissertation --- Master's Thesis, McGill University, | Master. Google Scholar

23. Robinson, J. P., S. W. Kingman, R. C. Barranco, E. Snape, and H. Al-Sayegh, "Microwave pyrolysis of wood pellets," Ind. Eng. Chem. Res., Vol. 49, No. 2, 459-463, 2010.
doi:DOI: 10.1021/ie901336k Google Scholar

24. Al-Sayegh, H., J. Robinson, G. Dimitrakis, and S. Kingman, "Microwave processing of forestry waste," IET RF and Microwave Network and National Centre for Industrial Microwave Processing (NCIMP), December 2010. Google Scholar

25. Dominguez, A., M. A. Menendez, et al. "Conventional and microwave induced pyrolysis of coffee hulls for the production of a hydrogen rich fuel gas," J. Anal. Appl. Pyrolysis, Vol. 79, No. 1--2, 128-135, 128.
doi:DOI: 10.1016/j.jaap.2006.08.003 Google Scholar

26. Goss, W. P. and R. G. Miller, "Thermal properties of wood and wood products," Proceedings of the Thermal Performance of the Exterior Envelopes of Whole Buildings International Conference, 1992, Sept. 2013.
doi:http://web.ornl.gov/sci/buildings/2012/1992%20B5/028.pdf Google Scholar

27. Center for Solid State Science "Mass density in Engineered materials," Arizona State University, Sept. 2013.
doi:http://invsee.asu.edu/nmodules/engmod/propdensity.html Google Scholar

28. Picard, S., D. T. Burns, and P. Roger, "Measurement of the specific heat capacity of graphite," Rapport BIPM-2006/01, 2006.
doi:www.bipm.org/utils/common/pdf/rapportBIPM/2006/01.pdf. Google Scholar

29. Clark, R. N., "Dielectric properties of materials," Kaye and Laby Online: Tables of Physical and Chemical Constants, 1995, Sept. 2013.
doi:http://www.kayelaby.npl.co.uk/general physics/2_6/2 6 5.html Google Scholar

30. Ida, N., "Magnetic properties of materials," Engineering Electromagnetics, 2004. Google Scholar

31. Ayappa, K. G., H. T. Davis, E. A. Davis, and J. Gordon, "Two-dimensional finite element analysis of microwave heating," AIChE Journal, Vol. 38, No. 10, 1577-1592, 1992.
doi:DOI: 10.1002/aic.690381009 Google Scholar

32. Zheng, F., Z. Chen, and J. Zhang, "Toward the development of a three-dimensional unconditionally stable finite-difference time-domain method," IEEE Transactions on Microwave Theory And Techniques, Vol. 48, No. 9, 1550-1558, 2000.
doi:DOI: 10.1109/22.869007 Google Scholar

33. COMSOL Multiphysics "Chemical reaction engineering module (Version 4.1a),", 2012.
doi:http://www.comsol.com/ Google Scholar

34. Zuo, W., Y. Tian, and R. Ren, "The important role of microwave receptors in bio-fuel production by microwave-induced pyrolysis of sewage sludge," Waste Management, Vol. 31, 1321-1326, 2011. Google Scholar

35. Fernandez, Y., A. Arenillas, and J. A. Menendez, "Microwave heating applied to pyrolysis," Advances in Induction and Microwave Heating of Mineral and Organic Materials, 724-752, 2011.
doi:DOI: 10.5772/13548 Google Scholar

36. Oloyede, A. and P. Groombridge, "The influence of microwave heating on the mechanical properties of wood," Journal of Materials Processing Technology, Vol. 100, 67-73, 2000.
doi:10.1016/S0021-9673(03)01176-2 Google Scholar

37. Yu, F., P. H. Steele, and R. Ruan, "Microwave pyrolysis of corn cob and characteristics of the pyrolytic chars," Energy Sources , Vol. 32, 475-484, 2010. Google Scholar

38. Demirbas, A., "Effects of temperature and particle size on biochar yield from pyrolysis of agricultural residues," J. Anal. Appl. Pyrolysis, Vol. 72, 243-248, 2004. Google Scholar

39. Dutta, B., "Assessment of pyrolysis techniques of lignocellulosic biomass for biochar production," Dissertation --- Master's Thesis, McGill University, 2010. Google Scholar

40. Uemura, Y., W. N. Omar, S. Razlan, H. Mif, S. Yusup, and K. Onoe, "Mass and energy yields of bio-oil obtained by microwave-induced pyrolysis of oil palm kernel shell," Journal of the Japan Insdture of Energy, Vol. 91, 954-959, 2012. Google Scholar

41. Dominguez, A., J. A. Menendez, M. Inguanzo, P. L. Bernad, and J. J. Pis, "Gas chromatographic-mass spectrometric study of the oil fractions produced by microwave-assisted pyrolysis of different sewage sludges," Journal of Chromatography A, Vol. 1012, No. 2, 193-206, 2003.
doi:DOI: 10.1016/S0021-9673(03)01176-2 Google Scholar

Dr. Baishali Dutta

Dr. Satyanarayan R. S. Dev

Dr. Vijaya G. S. Raghavan