Influence of spruce wood properties on thermomechanical pulping - pilot scale results_

摘要

Variation in wood characteristics within a single species can lead to significant changes in pulp properties and also energy requirements to reach a given level of fiber development. This study investigates thermomechanical pulping of Norway spruce wood furnishes obtained from three European countries, Norway, Sweden and France. Six wood sortments from each country were supplied, amounting to a total of eighteen wood sortments. The sortments were segregated on the basis of wood density and wood virgin fiber length. Basic density ranged from 332 kg/ m~3 to 435 kg/m~3. Virgin fiber length ranged from 2.1 mm to 3.2 mm. In addition to conventional TMP pulping, high-intensity thermomechanical pulps were also produced from many of the wood sortments. Distinct differences in pulp properties and energy requirements were observed between the different wood samples. Pulps produced from the long fiber/high density wood had the highest tear index and lowest scattering coefficient, and also lower energy-consumption. Pulps from the short fiber/low density wood had the highest scattering coefficient but lower tear index. Most of the pulps produced at high intensity refining conditions had similar pulp strength, lower energy consumption and higher brightness than the conventional TMP pulps. Relationships were also established for several paper properties versus virgin fiber length and wood basic density. The results provide information that can be used to specify optimal wood properties for optimization of specific paper properties, such as strength, optical properties and surface smoothness. This pilot plant trial is a part of the EuroFiber project.