Design and scheduling of Pharmaceutical Manufacturing Facilities - Towards modular processes

Batch processes offer the advantage of being able to produce several compounds, often with high added value, from standard equipment. They also offer the possibility of adapting to frequent market fluctuations. In general, each product has its own manufacturing method – the – recipe, which consists of a succession of steps linked together by technical constraints or prior art relationships.

This type of production, based on batch processes, is widely used in the fine and specialty chemicals industries, in multi-product or multi-purpose installations.

The specific characteristics of these industries have led process engineering specialists to take an interest in the management, scheduling and design of batch plants for several years now.

Over the last ten years or so, there has been a growing interest in optimizing and integrating the design and management of these processes. This article reviews the main concepts associated with this theme and illustrates them through several case studies.

These problems involve complex decisions concerning the allocation of product batches to specific recipe stages and equipment, at defined time intervals. Compared with continuous processes, this management has a marked combinatorial aspect and relies on discrete decisions. Drawing on a wealth of work in the field of operations research, this article looks at the specific features of process industries, particularly in the pharmaceutical sector (recipes, production campaigns, storage policies, performance criteria).

However, these processes have certain limitations, notably the intensive use of reagents and solvents, and the complexity of the scale-up stage. To meet these challenges, reconfigurable modular workshops are emerging as a promising solution. Indeed, continuous flow chemistry processes offer many advantages over batch processes. Thanks to the miniaturization of equipment, they can intensify transfers (heat, material, mixing), improve control of reaction conditions, resolve the inefficiency of heating/cooling systems, limit the formation of by-products and improve safety management. The literature review highlights the importance of developing systemic modeling approaches for the design and scheduling of reconfigurable modular workshops, building on the many existing methods and tools for batch processes.