Achieving Fast Paper Shade Change, 2001 Process Control, Electrical & Info. Conference Proceedings

Timothy F. Murphy, Shih-Chin Chen, George McKeague--For paper machines, which use dye additives to produce colored paper products, color (shade) changes can be a very time consuming process. Difficulties that are experienced in achieving the new product color can result in a large amount of production loss. Also, off spec colored paper is very undesirable because it can only be re-used during a similar color production run. This paper presents a control feature, which achieves faster color changes. By considering an estimate of the normalized dye usage from previous production runs an estimate of the required dye usage for color changes can be determined. Also, with the large volume of wet end re-circulation, dye addition changes can take a long time to establish when producing a new product color. By incorporating a boosting action into the dye addition changes wet-end dye change times are reduced. With both the dye usage estimate and boosting action significant reduction in color change times are observed on paper machines with this control feature.