Introducing a new operational policy: The PIS operational policy

A novel operational policy, the Process Intermediate Storage operational policy, is introduced and used to synthesize, schedule and design multipurpose batch plants. The model is based on the State Sequence Network and non-uniform discretization of the time horizon of interest model developed by Majozi and Zhu [Majozi, T., Zhu, X. (2001). A novel continuous-time MILP formulation for multipurpose batch plants. 1. Short-term scheduling. Industrial and Engineering Chemistry Research, 40(23), 5935–5949]. Two cases are studied to determine the effectiveness of this operational policy. In the first case, which excludes any dedicated storage, the use of this operational policy results in 50% improvement in throughput. The second case is used to determine the minimum amount of intermediate storage while maintaining the throughput achieved with infinite intermediate storage. This results in 20% reduction in the amount of dedicated intermediate storage. The models developed for both cases are MILP models. An MINLP design model is then developed to exploit the attributes of the PIS operational policy.