A new strategy for exploiting the recipe flexibility in batch industrial plants

S. FERRER-NADAL; C.A. MÉNDEZ; M. GRAELLS; L. PUIGJANER

Prague - Czech Republic

Conferencia; PRES 2006 (9th Conference on Process Integration, Modelling and Optimisation; 2006

Czech Society of Chemical Engineering

This work presents a rigorous mathematical strategy to optimize the maintenance operations of flexible batch recipes with continuous decaying performance. In this case, batches of the same product can be continuously produced at expense of degrading the product quality and/or increasing the expected processing time. This poses a trade-off between executing the required cleaning actions to return to the nominal production values and modifying production parameters to avoid performing expensive and nonproductive maintenance activities. Based on a continuous-time domain representation and the notion of immediate precedence, the overall problem is formulated as a mixed integer linear programming (MILP) model to the short-term scheduling of single stage multiproduct batch plants. The proposed mathematical programming formulation is able to determine the optimal production and maintenance schedule that maximizes the net profit, which takes into account operating and maintenance cost, revenues from product sales and penalties for late production orders. Also, useful heuristic strategies are described to easily prune the full search space and reduce the computational effort. The proposed approach is implemented within the GAMS modeling system and its efficiency and applicability are validated by successfully solving different case studies.