In this paper, a novel solution approach to addressing the problem of efficient reactive scheduling in multiproduct batch plants is presented. The approach is based on a two-stage solution procedure whereby, at the first stage, the deterministic schedule is established on the basis of data at the current time and, at the second stage, the optimal reschedule is obtained from the solution of a proposed formulation that systematically incorporates all different rescheduling alternatives. Two kinds of disturbances are considered - machine breakdown and rush order arrival. The rescheduling problem is formulated as a mixed integer linear programming (MILP) problem using a continuous time formulation, which leads to a smaller number of binary variables for both the deterministic and the rescheduling problems thus, resulting in reduced computational times. It is shown that the proposed approach results in an efficient utilization of the plant capability as it allows the optimal selection among all rescheduling alternatives in a systematic way without the use of any heuristics. Moreover, the objective function used allows the decision maker to determine the optimal reschedule in terms of profitability and plant operability by allowing the selection of a rescheduling policy close to the original schedule. The effectiveness of the proposed approach is illustrated through a number of case studies from scheduling literature for both single and multiple disturbances.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering