Analysis of The Fluidized Bed Drying of Wood Particles
Keywords:Drying curves, moisture content, heat transfer, mass transfer, design parameters
AbstractEngineering parameters necessary to design an industrial, continuous fluidized-bed dryer for wood particles were examined using a 0.21-m square batch fluidized-bed dryer. Parameters of main interest were gas velocity and drying curves, but bed voidage, particle elutriation, and distributor plate design also were considered. For unscreened (mixed sizes) hammermilled wood and sawdust, the minimum gas velocities for fluidization were 1.03 and 0.55 m/s, respectively. These values increased with increasing moisture content, decreasing sphericity, and increasing particle diameter. Current methods of adjusting batch drying curves so that they can be applied to a commercial continuous dryer were shown to be inadequate for some wood particle sizes. To predict drying curves for all particle sizes, a new method was developed that accounts for both internal and external resistances to drying. The new method was confirmed experimentally.
Carruthers, J. F. S., and M. S. Burridge. 1964. The drying of veneers in a fluid bed. For. Prod. J. 14(6):251-253.nCorder, S. E. 1958. Suspension drying of sawdust. For. Prod. J. 8(1):5-10.nCowan, C. B., W. S. Peterson, and G. L. Osberg. 1958. Spouting of large particles. Eng. J. 41(5): 60-64.nFefilov, V. V., and A. I. Sokolova. 1959. Drying of wood particles in a fluidized bed. Sb. Tr. Tsentr. Nauchno-Issled. Lesokhim. Inst. 13:3-15.nKanury, A. M. 1975. Introduction to combustion phenomena. Gordon and Breach, New York.nKobyl'Skikh, A. P., and V. N. Petri. 1966. Drying sawdust in a fluidized bed. Derevoobrab. Promst. 15(7):7.nKumar, R., K. V. Balachandran, and R. N. Kumar. 1971. Preliminary studies on the drying of sawdust in a fluidized bed. J. Indian Acad. Wood Sci. 2(1):32-37.nKunii, D., and O. Levenspiel. 1977. Fluidization engineering. John Krieger Publishing, Inc., New York.nLoos, W. E. 1971. Fluidized bed drying of southern pine veneer. For. Prod. J. 21(12):44-49.nLoos, W. E., and C. Y. Wen. 1970. Fluidized bed drying of yellow poplar veneer. For. Prod. J. 20(6): 56-58.nLuckins, J., and C. A. O. Sutherland. 1962. Fluidized bed drying of paper and board. Pages 238-242 in Proceedings from the Symposium on the Interactions between Fluids and Particles, London. Institute of Chemical Engineering, New York.nMilota, M. R. 1984. Engineering study on the drying wood particles in a fluidized bed. Ph.D. dissertation, Oregon State University, Corvallis.nReay, D., and R. W. K. Allen. 1982a. The effect of temperature on fluid bed batch drying curves. J. Sep. Process Technol. 3(4): 11-13.nReay, D., and R. W. K. Allen. 1982b. Predicting the performance of a continuous, well-mixed fluidized bed dryer from batch tests. Pages 130-140 in Proceedings of the Third International Drying Symposium. Hemisphere, New York.nVanecek, V., R. Drbohlav, and M. Markvart. 1962. Calculation of continuous fluidized bed drying equipment based on laboratory tests. Pages 233-237 in Symposium on the Interaction between Fluids and Particles, London. Institute of Chemical Engineering, New York.nWen, C. Y., and W. E. Loos. 1969. Rate of veneer drying in a fluidized bed. Wood Sci. 2(2): 87-90.n
The copyright of an article published in Wood and Fiber Science is transferred to the Society of Wood Science and Technology (for U. S. Government employees: to the extent transferable), effective if and when the article is accepted for publication. This transfer grants the Society of Wood Science and Technology permission to republish all or any part of the article in any form, e.g., reprints for sale, microfiche, proceedings, etc. However, the authors reserve the following as set forth in the Copyright Law:
1. All proprietary rights other than copyright, such as patent rights.
2. The right to grant or refuse permission to third parties to republish all or part of the article or translations thereof. In the case of whole articles, such third parties must obtain Society of Wood Science and Technology written permission as well. However, the Society may grant rights with respect to Journal issues as a whole.
3. The right to use all or part of this article in future works of their own, such as lectures, press releases, reviews, text books, or reprint books.