Dynamic Modeling of Batch-Type Operating Systems for Capital Cost Estimations, 2001 Pulping Conference Proceedings

T. Retsina, A. Trypakis, A. Ahlen--Dynamic modeling has been used for estimating storage capacities required in various alternative configurations in a batch-type Kraft mill. The mill is swinging between softwood and hardwood using partly common lines. The purpose was to determine the most cost effective approach for a proposed capital project and to evaluate investments in process equipment versus storage tanks.

A model describing the main operation, including the most important tanks of the pulp mill, was built. The model was run for numerous swing cycles. The production rate for each individual department, the respective inventory size and the period (time) of a swing cycle were all modulated. In each case examined, one of these three variables was fixed, while the second was changed in order to optimize the third.

In general, it was demonstrated that a well designed production strategy is the key to maximizing the duration of a swing cycle, or minimizing the inventory size.