Effects of Species, Specimen Size, and Heating Rate on Char Yield and Fuel Properties


  • Gwen L. Stimely
  • Paul R. Blankenhorn


Pyrolysis, char, gross heat of combustion


Char yields from red maple, white oak, longleaf pine, and hybrid poplar (NE 388) wood specimens of four different particle sizes carbonized in a flowing nitrogen atmosphere with heating rates of 5, 15, and 25 C/min up to 250 C, 400 C, and 600 C were examined. Although species, particle size, and heating rate trends were evident, regression analysis showed final carbonization temperature to be the most important factor influencing char yield.

Carbonized and noncarbonized specimens were subjected to elemental analysis and gross heat of combustion determinations. Regression analysis established a significant relationship of carbon and hydrogen content with final carbonization temperature. A linear relationship was found between gross heat of combustion values and carbon contents of wood and char specimens. An equation to theoretically calculate gross heat of combustion values of wood and char was developed through modification of Dulong's formula.


Babcock, G. H., and S. Wilcox. 1975. Steam—its generation and use. The Babcock and Wilcox Co., NY. pp. 6-5-6-6.nBaileys, R. T., and P. R. Blankenhorn. 1982. Calorific and porosity development in carbonized wood. Wood Sci. 15(1):19-27.nBeall, F. C. 1969. Thermogravimetric analysis of wood lignin and hemicelluloses. Wood Fiber 1(3):215-226.nBeall, F. C. P. R. Blankenhorn, and G. R. Moore. 1974. Carbonized wood—physical properties and use as an SEM preparation. Wood Sci. 6(3):212-219.nBlankenhorn, P. R., G. M. Jenkins, and, D. E. Kline. 1972. Dynamic mechanical properties and microstructure of some carbonized hardwoods. Wood Fiber 4(3):212-224.nBlankenhorn, P. R., D. P. Barnes, D. E. Kline, and W. K. Murphey. 1978. Porosity and pore size distribution of black cherry carbonized in an inert atmosphere. Wood Sci. 11(1):23-29.nBowersox, T. W., P. R. Blankenhorn, and W. K. Murphey. 1979, Heat of combustion, ash content, nutrient content, and chemical content of Populus hybrids. Wood Sci. 11(4):257-261.nCheremisinoff, P. N., and A. C. Morresi. 1976. Energy from solid wastes. Marcel Dekker, Inc., New York, pp. 363-366.nDemeter, J. J., C. R. McCann, J. M. Ekmann, and D. Bienstock. 1977. Combustion of char from pyrolyzed wood waste, NTIS Energy Research Abstracts, ABS. No. 54088, Pittsburgh Energy Research Center, pp. 1-25.nHammond, V. L., L. K. Mudge et al. 1974. Energy from forest residuals, by gasification of wood wastes. Pulp Paper 48(2):54-57.nKanury, A. M. 1972. Thermal decomposition kinetics of wood pyrolysis. Combustion Flame 18:75-83.nKnight, J. A., and M. D. Bowen. 1975. Pyrolysis—a method for conversion of forestry wastes to useful fuels. Southeast Tech. Div. of American Pulpwood. Association, Fall Meeting.nKoch, P. 1972. Utilization of the southern pines, vol. I. USDA For. Serv., So. For. Exp. Sta., Agric. Handbook No. 420, pp, 188-226.nLewellen, P. C., W. A. Peters, and J. B. Howard. 1976. Celoulose pyrolysis kinetics and char formation mechanism. 16th symposium on combustion. Fire Expl. Res. 1471-1480.nLunden, G. W. 1982. Selected properties and char yield of wood carbonized in a nitrogen atmosphere. M.S. thesis, The Pennsylvania State University. 70 pp.nMcGinnes, E. A., Jr., S. A. Kandeel, and P. S. Szofa. 1971. Some structural changes observed in the transformation of wood into charcoal. Wood Fiber 3(2):77-83.nMilne, T. 1979. Pyrolysis—the thermal behavior of biomass below 600†;C. In Vol. II—Principles of gasification. Solar Energy Research Institute, CO. Pp. 97-122.nMoore, G. R., P. R. Blankenhorn, F. C. Beall, and D. E. Kline. 1974. Some physical properties of birch carbonized in a nitrogen atmosphere. Wood Fiber 6(3):193-199.nPanshin, A. J., and C. de Zeeuw. 1970. Textbook of wood technology. McGraw-Hill Book Company, New York. 705 pp.nReed, T. B., and D. Jantzen 1979. A survey of biomass gasification. In Vol. II—Principles of gasification. Solar Energy Research Institute, CO. 123-117.nRoberts, A. F. 1970. A review of kinetics data for the pyrolysis of wood and related substances. Combustion Flame 14:261-371.nShafizadeh, F. 1968. Pyrolysis and combustion of cellulosic materials. Adv. Carbohydrate Chem. 23:419.nShafizadeh, F. 1980. Introduction to pyrolysis of biomass. Specialists' Workshop on Flash Pyrolysis of Biomass Proceedings, Solar Energy Res. Institute of DOE, CO. Pp. 79-101.nSlocum, D. H., E. A. McGinnes, Jr., and F. C. Beall. 1978, Charcoal yield, shrinkage, and density changes during carbonization of oak and hickory woods. Wood Sci. 11(1):42-47.nSusott, R. A. 1980. Effect of heating rate on char yield from forest fuels. USDA For. Serv. Res. Note, INT-295, Intermountain For, and Range Exp. Sta., Utah, pp. 1-6.nSusott, R. A., W. F. DeGroot, and F. Shafizadeh. 1975. Heat content of natural fuels. J. Fire Flamm. 6:311-325.nWenzl, H. F. J. 1970. The chemical technology of wood. Chapter 2. Academic Press, New York, Pp. 260-300.n






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