A Computer-Based Production Control System for the Coordination of Operations in a Pulp and Paper Mill

Abstract

An integrated pulp and paper mill constitutes a rather complex system, being composed of a number of production departments and with storage capacities between these departments.The purpose of a computer-based production control system is to reduce the effects of breakdowns and other disturbances in such a production system. Efficient coordination of the different production departments of the mill is achieved by efficient utilization of the existing storage capacities.A system with the above purpose has been developed at the Swedish Forest Products Research Laboratory and was installed in 1975 in the integrated pulp and board mill at Iggesund. A second, expanded system, is now being installed in cooperation with ASEA AB and Stora Kopparberg in the pulp mill at Skutskär. The system, which uses the mill’s process computer and on-line information system, includes an algorithm, based on network flow technique, that calculates a plan with suggested production rates in the different departments on the basis of known restrictions. The plan is specified hour by hour during the planning period (2 days). The plan can also be manually adjusted. Together with the plan different consequences of it, such as the development of storage tank levels production volumes or energy balances, are presented on display screens.