Simultaneous maintenance considerations and production planning in multi-purpose plants

The derivation of optimal production and optimal maintenance plans in multi-purpose process plants are dynamically interacting problems which cannot be treated independent of one another, especially since in the event of equipment failure the execution of processing tasks can be transfered to other suitable multi-purpose equipment. In this work, a general optimization framework is proposed incorporating both the maintenance as well as the production planning model and providing the necessary links to quantify the strong interactions between them. As an example, the problem of optimally allocating maintenance crews to different equipment components over different operating periods is examined. In this case, the maintenance model corresponds to a continuous time Markov chain which is integrated and simultaneously optimized with the production planning model to provide the optimal maintainability and production patterns. The comparison of the solution against a traditional approach, in which detailed process considerations are not taken into account, clearly illustrates the advantages of the proposed methodology