Pulp, Paper and Board pp 18-24 | Cite as
Contract n° BOS-137-S
Summary
The energy consumption during fatigue of wood has been investigated in order to elucidate ways of reducing the energy demand in thermomechanical and chemithermomechanical pulping processes. Thus, wood samples have been compressed cyclically under defined mechanical conditions in an environment comparable to that prevailing in refiners. By the use of fatigue studies it has been possible to deduce separately the influence of various process parameters on the fiber flexibilization process occuring in refiners. It is demonstrated that it is possible to extrapolate fatigue data from laboratory experiments, in the Hz-range, to the conditions of commercial refiners, i.e. in the kHz range. The fatigue studies indicate that energy savings in refining might be achieved by either increasing the temperature during refining or reducing the frequency of the mechanical treatment, i.e. reducing the refiner speed. Sulfonation is shown to reduce the energy demand during fatigue only at high degrees of sulfonation. This is partly a result of the greater differential between the refining temperature and the softening temperature for highly sulfonated wood, but, primarily a result of the reduced stiffness of the wood fibers.
Keywords
Wood Sample Wood Fiber Softening Temperature Mechanical Pulp Cyclic CompressionPreview
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