OPTIMAL PERIODIC SCHEDULING OF MULTIPURPOSE PLANTS IN THE CONTINUOUS-TIME DOMAIN

This paper considers the problem of determining an optimal periodic sc hedule for multipurpose plants comprising batch, semi-batch and contin uous operations. This aims to determine both the optimal duration of t he operating cycle, and the precise nature and timing of operations ta king place within it. The basis of our formulation is the general Reso urce-Task Network process representation coupled with a continuous rep resentation of time. The presented mathematical formulation results in a non-convex mixed integer nonlinear programming (MINLP) problem. The paper describes a special branch-and-bound algorithm for solving this problem by branching oil both discrete and continuous variables. The overall approach is demonstrated with an example.