Recycle Advanced Control Package

An upper-midwest, multi-source, 250 TPD recycle tissue mill increased its capacity utilizing a distributed control system advanced control package (ACP) to optimize plant processes from the pulpers through the bleach plant. An application node on the plant-wide network was used for the implementation of the ACP. The main objectives of the package were to increase throughput, decrease chemical consumption, decrease quality parameter variability, provide operator decision support tools including automatic grade change, automatic tuning and correction of in-line sensors, automatic production rate change, and statistical process control (SPC). Inherent in this Recycle Advanced Control Package is the premise that the plant operator knows the peculiarities of the process intimately and, in fact, better than anyone else. Furthermore, when given the most accurate, current information relating to this process in a timely basis; the operator can make the best and most informed decisions to assure the optimum quality of the final product, in this case, recycled mixed office waste.. An interface to the existing mill-wide computer via a personal computer to a distributed control system (DCS) link was used to enter and/or transfer data from the existing warehouse management system allowing for the matching of process and laboratory data for each batch. This information included the following: Supplier; Average Bale Weight; Purchase Order Number (if required); Grade; Pulper Number; Batch Number; on-line process sensor data; and laboratory test data. Tracking of the dirt and stickies content to a particular supplier allowed for the quality feedback parameters to be available on a timely basis in order to match them up with each batch. Results of rapid handsheet analysis were entered into the system via a menu approach. Selection of general results by the operator allowed for a quick determination of possible corrective action and automatic addition of chemicals.