Drying Rates of Wood Chips During Compression Drying

Compression drying is basically a process of forcing the free water in wood to move under high hydrostatic pressure through a solid structure. Fundamental information regarding the time-dependent characteristic of compression drying is necessary to develop efficient commercial processes. The purpose of this study is to provide an initial evaluation of the effect of some factors—pressure, wood density, and particle (chip) size—on free water extraction.Five species—aspen, balsam fir, jack pine, red maple, and red oak—were tested in this study. For each species both typical pulp size chips and particles from hammermilled chips were used. Drying rates were determined under constant ram face pressures at 500 psi, 1,000 psi, 1,500 psi, and 2,000 psi, respectively. The concept of drying rate is one of the important factors in dealing with compression drying, especially in designing dewatering pressure cycles.The most efficient compression drying is achieved during the first two minutes. Drying rates are negligible after 3 to 4 minutes of constant pressure in the 500 to 2,000 psi range. The analysis of variance for species shows highly significant differences in final moisture contents. Size of chips had a significant effect on final moisture contents Compressed density of hammermilled chips is slightly higher than that of unrefined chips. High density chips require higher pressure to initiate effective drying rates

Predicting Flexural Creep in Particleboard

An analytical expression that relates flexural creep behavior to time, temperature, and stress was used in this study to predict the long-time performance of a commercial particle-board from the short-time behavior exhibited in a conventional static bending test. The particleboard exhibited a hyperbolic deflection—log time relationship under all conditions studied while deflection predicted from tests at elevated temperature was nearly linear with log of time. Both Larson-Miller and Goldfein parameters provide reasonable estimates at low stress levels. At higher stress levels, the Larson-Miller parameter provides more conservative estimates of the behavior in the 1000-3000 hr range. Neither method predicts accurately the increasing creep rates at the high stress levels and longer times

Forest Products Research at U.S. Universities in 1982

This is a survey of professional staffing, research emphasis, and funding levels of the 37 universities in the United States that conduct forest products research. The survey was conducted by the Subcommittee on Forest Products Research, National Planning Group for Forestry (NPG-2)

The Simultaneous Drying and Densification of Sapwood

A process for densifying wood while simultaneously drying it in a platen press is described. The effect of various pressure-time functions on the density distribution of the final product is discussed as is the effect of these functions on the dimensional stability characteristics of the product. Low density wood of high permeability, generally sapwood, is applicable to this process. A product with the most uniform density distribution and the best stability characteristics is obtained by rapidly compressing the material after the center has reached 212 F. Springback of such material after soaking for three weeks amounts to 10 to 15%. More stable material can be produced by steeping green wood in phenol formaldehyde impregnating resin prior to drying and densification. Springback after soaking can then be reduced to 1 to 2%. The bending strength properties of the densified material was found to be proportional to the density in a range from 0.60 to 1.00 gm per cm3. Some estimates of cost of the process are presented

Hasil Hutan dan Ilmu Kayu : Suatu Pengantar

xviii.720 hal.;ill.;21 c

Hasil Hutan dan Ilmu Kayu suatu pengantar

xviii,719 hal,;ill,;22 c

Hasil Hutan dan kayu : Suatu Pengantar

xvi.719 hal.;ill.;21 c