NEW METHODOLOGY TO OPTIMIZE SORTING IN WOOD DRYING

One important problem in lumber drying is to maintain the lumber moisture content distribution within certain minimum and maximum values. Over-drying and under-drying are common causes for lower grade recovery and dimensional stability problems. It is known that both over-drying and underdrying can be reduced by sorting green lumber into different moisture content groups and sorting also offers the opportunity to redesign drying schedules. In this study, a new methodology was designed and tested to optimize kiln drying of lumber by implementing green sorting coupled with modified drying schedules. The methodology was applied to optimize the drying of 114 by 114mm2 hem-fir lumber sorted with an NMI capacitance type meter at a local sawmill. It was found that in comparison to unsorted lumber, sorting into three groups can reduce the drying time by 7% approximately and recover around 3/4 of the under-dried lumber. The experimental data on lumber degrade and moisture gradients measured after drying were also reported in this paper.

[1]  K. Abodayeh,et al.  PROBABILISTIC ANALYSIS AND DESIGN OF THE INDUSTRIAL TIMBER DRYING PROCESS , 2002 .

[2]  Western Dry Kiln Clubs,et al.  An example of operations research in the dry kilns , 1969 .

[3]  Stavros Avramidis,et al.  Annual ring orientation effect and slope of grain in hemlock timber drying , 2004 .

[4]  D. G. Arganbright,et al.  Green sorting incense-cedar for increased air-drying yard throughput , 1984 .

[5]  Diego Elustondo,et al.  Simulated comparative analysis of sorting strategies for RFV drying , 2003 .

[6]  Diego Elustondo,et al.  Comparative Analysis of Three Methods for Stochastic Lumber Drying Simulation , 2005 .

[7]  W. Simpson.  Dry kiln operator's manual , 1991 .

[8]  P. Baucour,et al.  Probabilistic Analysis of Timber Drying Schedules , 2003 .

[9]  S. Avramidis,et al.  Conventional kiln drying and equalization of Western hemlock (Tsuga heterophylla (Raf.)[Sarg]) to Japanese equilibrium moisture content , 2003, Holz als Roh- und Werkstoff.

[10]  Stavros Avramidis,et al.  Drying characteristics of hem-fir squares as affected by species and basic density presorting , 1996 .

[11]  Western Dry Kiln Clubs,et al.  A look at redry , 1973 .

[12]  W. L. James,et al.  Electric Moisture Meters for Wood. Revised. , 1984 .

[13]  C. J. Kozlik.  Kiln-drying incense-cedar squares for pencil stock , 1987 .

[14]  Ferhan Kayihan.  Stochastic Modeling of Lumber Drying in Batch Kilns , 1985 .

[15]  Stavros Avramidis,et al.  Stability study of square timbers in simulated house frame service in Japan , 2005 .

[16]  Michael R. Milota,et al.  Post sorting of hem-fir : a mill study , 1995 .

[17]  Diego Elustondo,et al.  The demonstration of increased fiber utilization using optimized lumber sorting and radio-frequency vacuum drying , 2003 .

[18]  Masatoshi Sugimori,et al.  Sorting sugi lumber by criteria determined with cluster analysis to improve drying , 2006 .