A novel approach to scheduling multipurpose batch plants using unit‐slots

Abstract

in Wiley InterScience (www.interscience.wiley.com).Several models for scheduling multipurpose batch plants exist in the literature. The models using unit-specific event points have shown better solution efficiency on various literature examples. This article presents a novel approach to scheduling multipurpose batch plants, which uses unit-slots instead of process-slots to manage shared resources such as material storage. We develop two slightly different models that are even more compact and simpler than that of Sundaramoorthy and Karimi, Chem Eng Sci. 2005;60:2679-2702. Although we focus on material as a shared resource, our multigrid approach rationalizes, generalizes, and improves the current multi-grid approaches for scheduling with shared resources. Our models allow nonsimultaneous transfers of materials into and out of a batch. We show by an example that this flexibility can give better schedules than those from existing models in some cases. Furthermore, our approach uses fewer slots (event-points) on some examples than even those required by the most recent unit-specific event-based model. Numerical evaluation using literature examples shows significant gains in solution efficiency from the use of unit-slots except where the number of unit-slots required for the optimal solution equals that of process slots. We also highlight the importance of constraint sequencing in GAMS implementation for evaluating mixed-integer linear programming based scheduling models fairly. V

Incorporating Enhanced Decision-Making Capabilities into a Hybrid Simulator for Scheduling of Batch Processes

“…This is also confirmed by the amount produced by simulation to be the same as the amount produced by the optimal solution. shown in the paper by Susarla et al [17]. The headings in this section match with the section headings in the reference.…”

“…Therefore, the results for only one sample case for each process are presented. For the ease of comparison, we have chosen those cases for which Gantt charts have been shown in the paper by Susarla et al [17]. The headings in this section match with the section headings in the reference.…”

“…The STNs are given in the Susarla paper [17]. The task and storage states in an STN have tasks with same names in the recipe network.…”

“…The headings in this section match with the section headings in the reference. References to other works are also available in the paper by Susarla et al [17]. To save space, only the recipe diagrams of the processes are given in various figures.…”

“…Therefore, a set of five representative problems was selected from the literature to illustrate specific capabilities of the BATCHES simulator. The details of the MP formulations and descriptions of underlying process for these examples are available in the paper by Susarla et al [17].…”