INTEGER PROGRAMMING-MODEL FOR THE GLOBALLY OPTIMAL SCHEDULE OF MULTIPURPOSE BATCH PLANTS

Scheduling becomes important for multipurpose batch plants from the point of their productivity, though it is very complicated since the making of a globally optimal schedule for such a plant requires that the operation sequences in all the equipment modules must be optimized simultaneously with consideration of the holding time and the clean-up time. Furthermore, these sequences interact with each other. In this study, an integer Programing model (IP-model) for the globally optimal schedule of multipurpose batch plants for given equipment module sequences of each product is developed. To formulate this model, the necessary constraints for optimization are considered and the variables to be introduced for describing them are examined. Moreover. these constraints are linearized by introducing integer variables and the sufficient large number for setting the boundaries to their nonlinear terms. The effectiveness of the proposed IP-model is illustrated by solving example scheduling problems.