Managing risk through a flexible recipe framework

Abstract

in Wiley InterScience (www.interscience.wiley.com).A novel approach is proposed that exploits the use of a flexible recipe framework as a better way to handle the risk associated with the scheduling under uncertainty of batch chemical plants. The proposed solution strategy relies on a novel two-stage stochastic formulation that explicitly includes the trade-off between risk and profit at the decision-making level. The model uses a continuous-time domain representation and the generalized notion of precedence. Management of risk is explicitly addressed by including a control measure (i.e., the profit in the worst scenario), as an additional objective to be considered, thus, leading to a multiobjective optimization problem. To overcome the numerical difficulties associated with such mathematical formulation, a decomposition strategy based on the sample average approximation (SAA) is introduced. The main advantages of this approach are illustrated through a case study, in which a set of solutions appealing to decision makers with different attitudes toward risk are obtained. The potential benefits of the proposed flexible recipe framework as a way of managing the risk associated with the plant operation under demand uncertainty are highlighted through comparison with the conventional approach that considers nominal operating conditions. Numerical results corroborate the advantages of exploiting the capabilities of the proposed flexible recipe framework for risk management purposes.

Operability Analysis of Process Supply Chains—Toward the Development of a Sustainable Bioeconomy

“…Variation in raw material quality, reduction of production cost by selecting cheaper recipes, and substitution due to material unavailability are the three main reasons that recipe flexibility is desired during manufacturing processes (Bertrand and Rutten, 1999). In addition, Ferrer-Nadal et al (2008) also demonstrate that the adoption of flexible recipes has a high benefit in risk management associated with uncertain demands. Therefore, the recipe flexibility shares some connection with both demand and supply uncertainty.…”

Improved Short-Term Batch Scheduling Flexibility Using Variable Recipes

“…In that work, the productivity maximization was established as an objective function and the cost of modifying process variables was considered negligible. In addition, Ferrer-Nadal et al incorporated the concept of recipe flexibility as an additional rescheduling action in the reactive batch operation of multipurpose batch plants. They assumed a linear model in a predefined flexibility region around nominal operating conditions, penalized any deviation from the optimal operating conditions, and solved a mixed-integral linear program (MILP), based on the general precedence model .…”

Integrated batch process development based on mixed-logic dynamic optimization

“…Historically, scheduling formulations rely on the use of approximated recipes represented by fixed times and size factor models, like in batch plant design. Some works proposed the use of flexible recipes in reactive scheduling approaches to deal with uncertainty through small modifications of processing conditions around nominal processing conditions (Ferrer-Nadal et al, 2007, 2008b. This way, most of the works searching optimal schedules are based on trade-offs strictly related to cycle time and equipment allocation.…”