Real-time production scheduling in a multi-purpose batch-oriented environment

The chemical company Omnichem has plants in Wetteren, Balen and Louvain-la-Neuve in Belgium. It has implemented an automated real-time batch-oriented scheduling procedure, in the first place for its synthesis plants on the Wetteren site. A constraint-based solution was chosen, taking into account the great number of rules and restrictions and the need to change the optimisation criterion when necessary (e,g. for just-in-time procedures). Within this context, interactive communication with the planner via a graphical user interface was absolutely essential. To guarantee a planning module that could meet Omnichem's requirements in a complex batch-oriented production environment, special features were employed such as artificial intelligence to guide the planner, an object-oriented database, interfaces with material requirement planning and process control, and flexible interaction with the scheduling system. This article outlines the definition of the problem, describes the design criteria for an automated real-time batch-oriented scheduler, and discusses the procedure followed to reach a solution. A short description is also included of the scheduling system actually implemented.