板紙グレード生産のブレード式トップフォーマの流体力学およびシート形成について: フォーミングセクション改造の評価

摘要

本報告では，板紙を抄造する旧式のブレード式トップフォーマを備えた長網抄紙機の改造について検証した.改造前の限界が基本的見地から討議され,旧式と改造ツインワイヤーフォーミングセクションの流体力学が調査された.改造前の限界を軽減するために，設計において挑戦と改善案が討議された.改造は最終製品の要求に基づいて具体的な原料と適用について専門的な考査がなされる.現設フォーミングセクションの大部分はそのまま残り，据付コストと停抄期間を最短にしている.%The rebuild of a fourdrinier with a vintage blade style top forming configuration is examined for paper machines producing board grades. Limitations of the pre-rebuild design are discussed from a fundamental standpoint. The fluid mechanics of the vintage and rebuild twin wire forming sections are examined. Design challenges and solutions to mitigate the limitations of the pre-rebuild former are discussed. The rebuild is engineered for the specific furnish and application based upon end product needs. A majority of the existing forming section remains intact minimizing installed cost and paper machine down time for installation. Three rebuilds are reported on, two on linerboard grades and one on a woodfree uncoated grade. Performance is characterized before and after each rebuild with regards to operating capacity and variety of sheet properties, depending on the grade of paper being produced. Significant improvements in capacity, formation, smoothness and mechanical strength properties were realized after the rebuilds.