OPERATING EXPERIENCES WITH THE LO-SOLIDS? PULPING PROCESS AT WILLAMETTE INDUSTRIES’ JOHNSONBURG MILL

摘要

In 1994 Willamette Industries’ Johnsonburg mill underwent a major, mill wide expansion andrnmodernization. As part of the new fiberline a single vessel hydraulic digester wasrncommissioned and then shortly afterwards converted to Lo-Solids cooking operations. Thisrnpaper describes the long term operating experiences with the Lo-Solids pulping process.rnCompared to earlier batch and earlier modified continuous operations, the Lo-Solids cookingrnoperation resulted in improved yield, washing, bleachability, pulp viscosity and paper machinernrunnability. Pulp yield was measured based on long term production and accounting data, andrnalso by using laboratory methods. The production and accounting data indicate a bleached yieldrnof 48.2%, while the laboratory based method indicates a bleached yield of 49.7%, both expressedrnas bone dry tons bleached pulp per bone dry ton of wood to the digester.