Operational envelopes for batch processes

• Published in: AIChE journal 2001-10, Vol.47 (10), p.2277-2288
• Main Authors: Samsatli, Nouri J., Sharif, Mona, Shah, Nilay, Papageorgiou, Lazaros G.
• Format: Article
• Language: English
• Subjects: Applications of mathematics to chemical engineering. Modeling. Simulation. Optimization; Applied sciences; Chemical engineering; Exact sciences and technology
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.690471013

Batch processes are often subjected to a number of sources of variability, which are frequently overlooked due to operating policy implementation. In many pharmaceutical and speciality chemical processes, which are predominantly batch in nature, a high proportion of the operating procedure is implemented manually, which can lead to significant variability. The effect of this variability is typically neglected at all stages in process development and even when full‐scale production begins. The result of any variability can have a dramatic effect on some process stages (particularly sensitive ones such as crystallization), and it is therefore important to understand how variability in any of the operating variables affects the overall process. Ideally, one would like to design processes that are less sensitive to variability and specify precisely the limits of any allowable variability. A method for designing batch processes using “operating envelopes” that specify process operation in terms of a region within which the operating variables should be maintained to guarantee feasible and profitable operation of the process is presented. The problem is formulated as a multiscenario dynamic optimization problem, and an efficient hierarchical solution procedure is presented. Finally, the applicability of the procedure is demonstrated by using two example problems.