Activities for Reduction of Bleaching Chemicals in Sendai Mill

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  • 川内工場における漂白薬品低減の取り組み
  • センダイ コウジョウ ニ オケル ヒョウハク ヤクヒン テイゲン ノ トリクミ

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Abstract

<p>The pulp & paper industry has been facing a challenging situation of lower demand and pricing due to declining domestic population and shift from paper to digital media. This has forced every paper industry to look at opportunities of reducing their costs. Since pulp is the single largest cost in paper making, pulp mills have been forced to reduce their costs in turn. The kraft pulp production lines at Sendai mill of Chuetsu Pulp & Paper Industries has two lines ines g due to declining dome （LBKP） and a batch digester line （NUKP, NBKP）．The bleach plant with 3-stage bleaching （D0-EP-D1） was suffering from high bleaching chemical costs in addition to high brightness variability.</p><p>The two key factors responsible for these high costs were ［1］ The bleach plant does not have an Acid Stage （A-Stage） due to which uncontrolled and high carryover of hexenuronic acid （hereinafter called HexA） entered into the bleaching which in turn consumes higher Chlorine Dioxide （ClO2）．［2］ The bleach plant was overdosing bleaching chemicals & running higher brightness to remain safe with quality specifications.</p><p>To address the above mentioned challenges, Sendai mill installed a chlorine dioxide/ peroxymonosulfuric acid combination dosing equipment on D0-stage in 2018, which has helped significantly. To further fix the challenges associated with manual process control, operator bias, and ability for bleach plant to handle incoming variability, a Model Predictive Control system （MACS） together with bleach load analyzers was implemented across the whole bleaching process in 2019. These projects have resulted into significant reduction in bleaching chemical costs and final brightness variability. This paper reports on details of these activities and obtained results.</p>

Journal

  • JAPAN TAPPI JOURNAL

    JAPAN TAPPI JOURNAL 75 (6), 531-535, 2021

    JAPAN TECHNICAL ASSOCIATION OF THE PULP AND PAPER INDUSTRY

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