Flexibility Assessment of a Distillation Train: Nominal vs Perturbated Conditions Optimal Design

Alessandro Di Pretoro (1, 2) , Ludovic Montastruc (1) , Flavio Manenti (2) , Xavier Joulia (1)

1 LGC - Laboratoire de Génie Chimique
2 POLIMI - Politecnico di Milano [Milan]

Multicomponent mixtures can be separated into their single components by mean of different distillation train configurations. The standard design procedure consists of the assessment of the optimal columns configuration according to the economic and operational aspects. Anyway this optimal design is strictly related to the operating conditions, i.e. perturbations, when present, can seriously turn the tables. In these cases a flexibility analysis could be of critical importance to assess the operating conditions range of better performance for a system configuration with respect to another one. This is the typical case of biorefineries (and bio-processes in general) where the composition perturbations downstream the fermenter across the year’s seasons are completely normal due to the floating nature of the feedstock. Since no similar studies have been found in literature, a brand new ABE/W (acetone, n-butanol, ethanol, water) mixture separation case study has been set up; this mixture derives from an upstream microbial conversion process and the successful recovery of at least biobutanol and acetone is crucial for the profitability of the operation. Therefore the purpose of this paper is the comparison between the possible distillation train configurations from a flexibility point of view. We are interested in particular in highlighting the differences, if present, between the economic optimal solution and flexibility optimal configuration that sometimes could not be the same, causing this way a very profitable design to be much less performant under perturbated conditions. The flexibility assessment has been performed with an established procedure introduced in previous papers; all the flexibility indexes proposed in literature have been used both of simple and most complex usage in order to refine the analysis and a flexibility economic assessment has been carried out as well. Finally the two different configurations as well as the two different procedures (operating conditions based vs perturbated conditions based) have been compared both from a design and an economic point of view; then analogies and differences as well as their consequences from a decision making point of view have been highlighted and discussed.

Mots clés: Flexibility analysis; Design optimization; Distillation; Column trains

Domaines: Génie chimique; Génie des procédés

Alessandro Di Pretoro, Ludovic Montastruc, Flavio Manenti, Xavier Joulia. Flexibility Assessment of a Distillation Train: Nominal vs Perturbated Conditions Optimal Design. Proceedings of the 29 th European Symposium on Computer Aided Process Engineering, Jun 2019, Eindhoven, Netherlands. pp.667-672, ⟨10.1016/B978-0-12-818634-3.50112-0⟩. ⟨hal-03621651⟩