Bleaching Optimization at WestRock, Covington, Virginia

摘要

The WestRock Covington VA mill, initiated a long term diagnostic and optimization program for all three of its bleaching lines. As part of that effort, benchmarking studies were used to help identify optimization opportunities for all three production lines at the mill. This paper will focus on the "B" line, producing southern hardwood pulp in a D(EP)DD sequence at 88 brightness. The benchmarking study and optimization work identified the following options for improved performance: 1. Non-optimal addition of caustic and hydrogen peroxide to the EP stage; 2. Carryover of Do filtrate to the EP stage; and 3. Carryover of EP filtrate to the D1 stage. The mill undertook a number of actions to address the opportunities identified. As a result: 4. Do kappa factor decreased ~ 5%; 5. NaOH consumption in the Ep stage decreased ～ 35%; 6. ClO_2 consumption in the D1 stage decreased ～ 25%; and 7. Overall bleaching cost decreased ～ 15%.